Article

To the Editor:

Necrobiotic xanthogranuloma (NXG) is classified as a cutaneous non–Langerhans cell histiocytosis, often seen with monoclonal gammopathy of undetermined significance or multiple myeloma.¹ Clinically, it appears as a red or yellow plaque with occasional ulceration and telangiectasias, most commonly seen periorbitally and on the trunk. On pathology, NXG appears as necrobiosis, giant cells, and various inflammatory cells extending into the subcutaneous tissue.² In this article, we describe a rare presentation of NXG in location and skin type.

A 52-year-old woman with a history of systemic lupus erythematosus (SLE) presented with alopecia and a tender lesion on the scalp of 5 years’ duration (Figure 1). The patient had no history of a similar lesion, and no other lesions were present. A biopsy performed at an outside clinic a few weeks to months prior to the initial presentation to our clinic showed NXG (Figure 2). Evaluation at our clinic revealed a 4x4-cm orange-brown annular plaque on the left parietal scalp. Serum and urine protein electrophoresis studies were negative. The patient reported she was up to date with recommended screenings such as mammography and colonoscopy. 

We started the patient on topical triamcinolone and topical ruxolitinib and administered intralesional triamcinolone. She was already taking hydroxychloroquine and leflunomide for SLE. Three weeks later, she returned with improved symptoms and appearance (Figure 1). She remained on intralesional triamcinolone and ruxolitinib and continues to experience improvement.

Necrobiotic xanthogranuloma is rare and typically is associated with monoclonal gammopathy.² In one study, 83 of 100 of patients with NXG presented with or were found to have a monoclonal gammopathy.² In another study, paraproteinemia was detected in 82.1% of patients.³ The majority of case reports and systematic reviews detail periorbital or thoracic lesions.⁴ The location on the scalp and lack of association with paraproteinemia make this a rare presentation of NXG. Studies may be warranted to explore any association of SLE with NXG if more cases present.

In a multicenter cross-sectional study and systematic review of 235 patients with NXG, 87% were White, 12% were Asian, and only 1% were Black or African American.³ The limited representation of skin of color raises concern for the possibility of missed diagnoses and delays in care. 

Treatment of NXG often is multimodal with use of intravenous immunoglobulin, oral steroids, chlorambucil, melphalan, and other alkylating agents, and response is variable.^3-6 Recent studies show treatment effectiveness with Janus kinase inhibitors in granulomatous dermatitides.^7-9 As our patient was not responding to prior treatments, we decided to try ruxolitinib, and she has continued to improve with it.^10,11 Interestingly, the patient experienced continued improvement with intralesional triamcinolone, which is not often reported in the literature.^2-6 Overall, NXG is an extremely rare condition that requires special care in workup to rule out paraproteinemia and a thoughtful approach to treatment modalities.

To the Editor:

Necrobiotic xanthogranuloma (NXG) is classified as a cutaneous non–Langerhans cell histiocytosis, often seen with monoclonal gammopathy of undetermined significance or multiple myeloma.¹ Clinically, it appears as a red or yellow plaque with occasional ulceration and telangiectasias, most commonly seen periorbitally and on the trunk. On pathology, NXG appears as necrobiosis, giant cells, and various inflammatory cells extending into the subcutaneous tissue.² In this article, we describe a rare presentation of NXG in location and skin type.

A 52-year-old woman with a history of systemic lupus erythematosus (SLE) presented with alopecia and a tender lesion on the scalp of 5 years’ duration (Figure 1). The patient had no history of a similar lesion, and no other lesions were present. A biopsy performed at an outside clinic a few weeks to months prior to the initial presentation to our clinic showed NXG (Figure 2). Evaluation at our clinic revealed a 4x4-cm orange-brown annular plaque on the left parietal scalp. Serum and urine protein electrophoresis studies were negative. The patient reported she was up to date with recommended screenings such as mammography and colonoscopy. 

We started the patient on topical triamcinolone and topical ruxolitinib and administered intralesional triamcinolone. She was already taking hydroxychloroquine and leflunomide for SLE. Three weeks later, she returned with improved symptoms and appearance (Figure 1). She remained on intralesional triamcinolone and ruxolitinib and continues to experience improvement.

Necrobiotic xanthogranuloma is rare and typically is associated with monoclonal gammopathy.² In one study, 83 of 100 of patients with NXG presented with or were found to have a monoclonal gammopathy.² In another study, paraproteinemia was detected in 82.1% of patients.³ The majority of case reports and systematic reviews detail periorbital or thoracic lesions.⁴ The location on the scalp and lack of association with paraproteinemia make this a rare presentation of NXG. Studies may be warranted to explore any association of SLE with NXG if more cases present.

In a multicenter cross-sectional study and systematic review of 235 patients with NXG, 87% were White, 12% were Asian, and only 1% were Black or African American.³ The limited representation of skin of color raises concern for the possibility of missed diagnoses and delays in care. 

Treatment of NXG often is multimodal with use of intravenous immunoglobulin, oral steroids, chlorambucil, melphalan, and other alkylating agents, and response is variable.^3-6 Recent studies show treatment effectiveness with Janus kinase inhibitors in granulomatous dermatitides.^7-9 As our patient was not responding to prior treatments, we decided to try ruxolitinib, and she has continued to improve with it.^10,11 Interestingly, the patient experienced continued improvement with intralesional triamcinolone, which is not often reported in the literature.^2-6 Overall, NXG is an extremely rare condition that requires special care in workup to rule out paraproteinemia and a thoughtful approach to treatment modalities.

To the Editor:

Necrobiotic xanthogranuloma (NXG) is classified as a cutaneous non–Langerhans cell histiocytosis, often seen with monoclonal gammopathy of undetermined significance or multiple myeloma.¹ Clinically, it appears as a red or yellow plaque with occasional ulceration and telangiectasias, most commonly seen periorbitally and on the trunk. On pathology, NXG appears as necrobiosis, giant cells, and various inflammatory cells extending into the subcutaneous tissue.² In this article, we describe a rare presentation of NXG in location and skin type.

A 52-year-old woman with a history of systemic lupus erythematosus (SLE) presented with alopecia and a tender lesion on the scalp of 5 years’ duration (Figure 1). The patient had no history of a similar lesion, and no other lesions were present. A biopsy performed at an outside clinic a few weeks to months prior to the initial presentation to our clinic showed NXG (Figure 2). Evaluation at our clinic revealed a 4x4-cm orange-brown annular plaque on the left parietal scalp. Serum and urine protein electrophoresis studies were negative. The patient reported she was up to date with recommended screenings such as mammography and colonoscopy. 

We started the patient on topical triamcinolone and topical ruxolitinib and administered intralesional triamcinolone. She was already taking hydroxychloroquine and leflunomide for SLE. Three weeks later, she returned with improved symptoms and appearance (Figure 1). She remained on intralesional triamcinolone and ruxolitinib and continues to experience improvement.

Necrobiotic xanthogranuloma is rare and typically is associated with monoclonal gammopathy.² In one study, 83 of 100 of patients with NXG presented with or were found to have a monoclonal gammopathy.² In another study, paraproteinemia was detected in 82.1% of patients.³ The majority of case reports and systematic reviews detail periorbital or thoracic lesions.⁴ The location on the scalp and lack of association with paraproteinemia make this a rare presentation of NXG. Studies may be warranted to explore any association of SLE with NXG if more cases present.

In a multicenter cross-sectional study and systematic review of 235 patients with NXG, 87% were White, 12% were Asian, and only 1% were Black or African American.³ The limited representation of skin of color raises concern for the possibility of missed diagnoses and delays in care. 

Treatment of NXG often is multimodal with use of intravenous immunoglobulin, oral steroids, chlorambucil, melphalan, and other alkylating agents, and response is variable.^3-6 Recent studies show treatment effectiveness with Janus kinase inhibitors in granulomatous dermatitides.^7-9 As our patient was not responding to prior treatments, we decided to try ruxolitinib, and she has continued to improve with it.^10,11 Interestingly, the patient experienced continued improvement with intralesional triamcinolone, which is not often reported in the literature.^2-6 Overall, NXG is an extremely rare condition that requires special care in workup to rule out paraproteinemia and a thoughtful approach to treatment modalities.

As the health care landscape continues to shift, direct care (also known as direct pay) models have emerged as attractive alternatives to traditional insurance-based practice. For dermatology residents poised to enter the workforce, the direct care model offers potential advantages in autonomy, patient relationships, and work-life balance, but not without considerable risks and operational challenges. This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The transition from dermatology residency to clinical practice allows for a variety of paths, from large academic institutions to private practice to corporate entities (private equity–owned groups). In recent years, the direct care model has gained traction, particularly among physicians seeking greater autonomy and a more sustainable pace of practice.

Direct care dermatology practices operate outside the constraints of third-party payers, offering patients transparent pricing and direct access to care in exchange for fees paid out of pocket. By eliminating insurance companies as the middleman, it allows for less overhead, longer visits with patients, and increased access to care; however, though this model may seem appealing, direct care practices are not without their own set of challenges, especially amid rising concerns over physician burnout and administrative burden. 

This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The Case for Direct Care Dermatology

Autonomy and Control—Perhaps the most compelling advantage of the direct care model is clinical and operational autonomy. Without insurance contracts dictating codes, coverage limitations, and documentation demands, physicians regain full control over their practice—how much time they spend with each patient, what treatments they offer, and how they structure their schedules. This option is ideal for those who want to practice medicine the way they were trained—thoroughly, thoughtfully, and without rushing.

Improved Work-Life Balance—The direct care model allows for smaller patient panels, longer visits, and more flexible hours. In contrast to the high patient volumes required to maintain profitability in insurance-based models, direct care dermatologists often can sustain their practice with a smaller number of daily appointments. This results in reduced administrative overhead and the potential for substantial reduction in burnout, a concern that has been well documented among dermatologists in high-volume settings.^1-3 As a result, physicians are less likely to rush through patient visits or be consumed by concerns of falling behind, ultimately causing them to question their career choice.

Closer Patient Relationships—With fewer patients and longer visits, dermatologists often find the direct care model fosters a stronger therapeutic alliance that can improve treatment adherence, outcomes, and overall patient satisfaction. Additionally, patients often appreciate transparent pricing, the ability to reach their dermatologist more directly, and a sense of being truly seen and heard. This, in turn, can make dermatology more rewarding for the provider.

Entrepreneurial Opportunity—Direct care offers entrepreneurial individuals the chance to build a brand and shape a niche. It also provides the flexibility to explore complementary or alternative practice models.

The Challenges of Going Direct

Despite its appeal, starting a direct care practice is not without substantial risks and hurdles—particularly for residents just out of training. These challenges include financial risks and startup costs, market uncertainty, lack of mentorship or support, and limitations in treating complex dermatologic conditions.

Financial Risk and Startup Costs—Launching any solo practice involves a considerable financial investment up front, including rent, medical equipment, electronic medical record systems, malpractice insurance, marketing, and staffing. In a direct care model, there is the added pressure of building a patient base without the referral stream of insurance contracts. In the first 6 to 12 months, income may be minimal, making this route challenging without savings, a financial cushion, or external funding.

Market Uncertainty—The success of direct care dermatology depends heavily on local market dynamics. In affluent or health-literate communities, patients may be more willing to pay out of pocket for expedited or personalized care; however, in other areas, patients may be unwilling or unable to do so—especially if they are accustomed to using insurance. Physicians may find that some of their patients will choose to see a different dermatologist for certain procedures because it is covered by their insurance.

Lack of Immediate Mentorship or Support—Transitioning from residency to independent practice (in any model) can be difficult. Residency provides a structured, team-based environment with colleagues and mentors at every turn. A solo or small-group direct care practice may feel isolating, especially in the early months. Without senior physicians to consult with on challenging cases or administrative decisions, the learning curve can be steep. Early-career dermatologists must be confident in their clinical acumen and be prepared to seek out alternative mentorship or continuing education opportunities.

Limitations in Complex Medical Dermatology—While direct care excels in most general dermatology visit types (from medical and cosmetic to minor surgical), this model may be less suited for patients requiring complex care coordination. Patients with high-cost conditions such as immunobullous diseases or those needing systemic immunosuppressives may still require referral to academic centers or insurance-covered specialists. Additionally, costlier procedures such as Mohs micrographic surgery may not fit well into a direct pay model, which may limit the scope of practice for direct care dermatologists in this subspecialty.

Considerations for Residents

Before committing to practicing via a direct care model, dermatology residents should reflect on the following:

• Risk tolerance: Are you comfortable navigating the business and financial risk?
• Location: Does your target community have patients willing and able to pay out of pocket?
• Scope of interest: Will a direct care practice align with your clinical passions?
• Support systems: Do you have access to mentors, legal and financial advisors, and operational support?
• Long-term goals: Are you building a lifestyle practice, a scalable business, or a stepping stone to a future opportunity?

Ultimately, the decision to pursue a direct care model requires careful reflection on personal values, financial preparedness, and the unique needs of the community one intends to serve.

Final Thoughts

The direct care dermatology model offers an appealing alternative to traditional practice, especially for those prioritizing autonomy, patient connection, and work-life balance; however, it demands an entrepreneurial spirit as well as careful planning and an acceptance of financial uncertainty—factors that may pose challenges for new graduates. For dermatology residents, the decision to pursue direct care should be grounded in personal values, practical considerations, and a clear understanding of both the opportunities and limitations of this evolving practice model.

As the health care landscape continues to shift, direct care (also known as direct pay) models have emerged as attractive alternatives to traditional insurance-based practice. For dermatology residents poised to enter the workforce, the direct care model offers potential advantages in autonomy, patient relationships, and work-life balance, but not without considerable risks and operational challenges. This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The transition from dermatology residency to clinical practice allows for a variety of paths, from large academic institutions to private practice to corporate entities (private equity–owned groups). In recent years, the direct care model has gained traction, particularly among physicians seeking greater autonomy and a more sustainable pace of practice.

Direct care dermatology practices operate outside the constraints of third-party payers, offering patients transparent pricing and direct access to care in exchange for fees paid out of pocket. By eliminating insurance companies as the middleman, it allows for less overhead, longer visits with patients, and increased access to care; however, though this model may seem appealing, direct care practices are not without their own set of challenges, especially amid rising concerns over physician burnout and administrative burden. 

This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The Case for Direct Care Dermatology

Autonomy and Control—Perhaps the most compelling advantage of the direct care model is clinical and operational autonomy. Without insurance contracts dictating codes, coverage limitations, and documentation demands, physicians regain full control over their practice—how much time they spend with each patient, what treatments they offer, and how they structure their schedules. This option is ideal for those who want to practice medicine the way they were trained—thoroughly, thoughtfully, and without rushing.

Improved Work-Life Balance—The direct care model allows for smaller patient panels, longer visits, and more flexible hours. In contrast to the high patient volumes required to maintain profitability in insurance-based models, direct care dermatologists often can sustain their practice with a smaller number of daily appointments. This results in reduced administrative overhead and the potential for substantial reduction in burnout, a concern that has been well documented among dermatologists in high-volume settings.^1-3 As a result, physicians are less likely to rush through patient visits or be consumed by concerns of falling behind, ultimately causing them to question their career choice.

Closer Patient Relationships—With fewer patients and longer visits, dermatologists often find the direct care model fosters a stronger therapeutic alliance that can improve treatment adherence, outcomes, and overall patient satisfaction. Additionally, patients often appreciate transparent pricing, the ability to reach their dermatologist more directly, and a sense of being truly seen and heard. This, in turn, can make dermatology more rewarding for the provider.

Entrepreneurial Opportunity—Direct care offers entrepreneurial individuals the chance to build a brand and shape a niche. It also provides the flexibility to explore complementary or alternative practice models.

The Challenges of Going Direct

Despite its appeal, starting a direct care practice is not without substantial risks and hurdles—particularly for residents just out of training. These challenges include financial risks and startup costs, market uncertainty, lack of mentorship or support, and limitations in treating complex dermatologic conditions.

Financial Risk and Startup Costs—Launching any solo practice involves a considerable financial investment up front, including rent, medical equipment, electronic medical record systems, malpractice insurance, marketing, and staffing. In a direct care model, there is the added pressure of building a patient base without the referral stream of insurance contracts. In the first 6 to 12 months, income may be minimal, making this route challenging without savings, a financial cushion, or external funding.

Market Uncertainty—The success of direct care dermatology depends heavily on local market dynamics. In affluent or health-literate communities, patients may be more willing to pay out of pocket for expedited or personalized care; however, in other areas, patients may be unwilling or unable to do so—especially if they are accustomed to using insurance. Physicians may find that some of their patients will choose to see a different dermatologist for certain procedures because it is covered by their insurance.

Lack of Immediate Mentorship or Support—Transitioning from residency to independent practice (in any model) can be difficult. Residency provides a structured, team-based environment with colleagues and mentors at every turn. A solo or small-group direct care practice may feel isolating, especially in the early months. Without senior physicians to consult with on challenging cases or administrative decisions, the learning curve can be steep. Early-career dermatologists must be confident in their clinical acumen and be prepared to seek out alternative mentorship or continuing education opportunities.

Limitations in Complex Medical Dermatology—While direct care excels in most general dermatology visit types (from medical and cosmetic to minor surgical), this model may be less suited for patients requiring complex care coordination. Patients with high-cost conditions such as immunobullous diseases or those needing systemic immunosuppressives may still require referral to academic centers or insurance-covered specialists. Additionally, costlier procedures such as Mohs micrographic surgery may not fit well into a direct pay model, which may limit the scope of practice for direct care dermatologists in this subspecialty.

Considerations for Residents

Before committing to practicing via a direct care model, dermatology residents should reflect on the following:

• Risk tolerance: Are you comfortable navigating the business and financial risk?
• Location: Does your target community have patients willing and able to pay out of pocket?
• Scope of interest: Will a direct care practice align with your clinical passions?
• Support systems: Do you have access to mentors, legal and financial advisors, and operational support?
• Long-term goals: Are you building a lifestyle practice, a scalable business, or a stepping stone to a future opportunity?

Ultimately, the decision to pursue a direct care model requires careful reflection on personal values, financial preparedness, and the unique needs of the community one intends to serve.

Final Thoughts

The direct care dermatology model offers an appealing alternative to traditional practice, especially for those prioritizing autonomy, patient connection, and work-life balance; however, it demands an entrepreneurial spirit as well as careful planning and an acceptance of financial uncertainty—factors that may pose challenges for new graduates. For dermatology residents, the decision to pursue direct care should be grounded in personal values, practical considerations, and a clear understanding of both the opportunities and limitations of this evolving practice model.

As the health care landscape continues to shift, direct care (also known as direct pay) models have emerged as attractive alternatives to traditional insurance-based practice. For dermatology residents poised to enter the workforce, the direct care model offers potential advantages in autonomy, patient relationships, and work-life balance, but not without considerable risks and operational challenges. This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The transition from dermatology residency to clinical practice allows for a variety of paths, from large academic institutions to private practice to corporate entities (private equity–owned groups). In recent years, the direct care model has gained traction, particularly among physicians seeking greater autonomy and a more sustainable pace of practice.

Direct care dermatology practices operate outside the constraints of third-party payers, offering patients transparent pricing and direct access to care in exchange for fees paid out of pocket. By eliminating insurance companies as the middleman, it allows for less overhead, longer visits with patients, and increased access to care; however, though this model may seem appealing, direct care practices are not without their own set of challenges, especially amid rising concerns over physician burnout and administrative burden. 

This article explores the key benefits and drawbacks of starting a direct care dermatology practice, providing a framework to help early-career dermatologists determine whether this path aligns with their personal and professional goals.

The Case for Direct Care Dermatology

Autonomy and Control—Perhaps the most compelling advantage of the direct care model is clinical and operational autonomy. Without insurance contracts dictating codes, coverage limitations, and documentation demands, physicians regain full control over their practice—how much time they spend with each patient, what treatments they offer, and how they structure their schedules. This option is ideal for those who want to practice medicine the way they were trained—thoroughly, thoughtfully, and without rushing.

Improved Work-Life Balance—The direct care model allows for smaller patient panels, longer visits, and more flexible hours. In contrast to the high patient volumes required to maintain profitability in insurance-based models, direct care dermatologists often can sustain their practice with a smaller number of daily appointments. This results in reduced administrative overhead and the potential for substantial reduction in burnout, a concern that has been well documented among dermatologists in high-volume settings.^1-3 As a result, physicians are less likely to rush through patient visits or be consumed by concerns of falling behind, ultimately causing them to question their career choice.

Closer Patient Relationships—With fewer patients and longer visits, dermatologists often find the direct care model fosters a stronger therapeutic alliance that can improve treatment adherence, outcomes, and overall patient satisfaction. Additionally, patients often appreciate transparent pricing, the ability to reach their dermatologist more directly, and a sense of being truly seen and heard. This, in turn, can make dermatology more rewarding for the provider.

Entrepreneurial Opportunity—Direct care offers entrepreneurial individuals the chance to build a brand and shape a niche. It also provides the flexibility to explore complementary or alternative practice models.

The Challenges of Going Direct

Despite its appeal, starting a direct care practice is not without substantial risks and hurdles—particularly for residents just out of training. These challenges include financial risks and startup costs, market uncertainty, lack of mentorship or support, and limitations in treating complex dermatologic conditions.

Financial Risk and Startup Costs—Launching any solo practice involves a considerable financial investment up front, including rent, medical equipment, electronic medical record systems, malpractice insurance, marketing, and staffing. In a direct care model, there is the added pressure of building a patient base without the referral stream of insurance contracts. In the first 6 to 12 months, income may be minimal, making this route challenging without savings, a financial cushion, or external funding.

Market Uncertainty—The success of direct care dermatology depends heavily on local market dynamics. In affluent or health-literate communities, patients may be more willing to pay out of pocket for expedited or personalized care; however, in other areas, patients may be unwilling or unable to do so—especially if they are accustomed to using insurance. Physicians may find that some of their patients will choose to see a different dermatologist for certain procedures because it is covered by their insurance.

Lack of Immediate Mentorship or Support—Transitioning from residency to independent practice (in any model) can be difficult. Residency provides a structured, team-based environment with colleagues and mentors at every turn. A solo or small-group direct care practice may feel isolating, especially in the early months. Without senior physicians to consult with on challenging cases or administrative decisions, the learning curve can be steep. Early-career dermatologists must be confident in their clinical acumen and be prepared to seek out alternative mentorship or continuing education opportunities.

Limitations in Complex Medical Dermatology—While direct care excels in most general dermatology visit types (from medical and cosmetic to minor surgical), this model may be less suited for patients requiring complex care coordination. Patients with high-cost conditions such as immunobullous diseases or those needing systemic immunosuppressives may still require referral to academic centers or insurance-covered specialists. Additionally, costlier procedures such as Mohs micrographic surgery may not fit well into a direct pay model, which may limit the scope of practice for direct care dermatologists in this subspecialty.

Considerations for Residents

Before committing to practicing via a direct care model, dermatology residents should reflect on the following:

• Risk tolerance: Are you comfortable navigating the business and financial risk?
• Location: Does your target community have patients willing and able to pay out of pocket?
• Scope of interest: Will a direct care practice align with your clinical passions?
• Support systems: Do you have access to mentors, legal and financial advisors, and operational support?
• Long-term goals: Are you building a lifestyle practice, a scalable business, or a stepping stone to a future opportunity?

Ultimately, the decision to pursue a direct care model requires careful reflection on personal values, financial preparedness, and the unique needs of the community one intends to serve.

Final Thoughts

The direct care dermatology model offers an appealing alternative to traditional practice, especially for those prioritizing autonomy, patient connection, and work-life balance; however, it demands an entrepreneurial spirit as well as careful planning and an acceptance of financial uncertainty—factors that may pose challenges for new graduates. For dermatology residents, the decision to pursue direct care should be grounded in personal values, practical considerations, and a clear understanding of both the opportunities and limitations of this evolving practice model.

Steatocystomas are small sebum-filled cysts that typically manifest in the dermis and originate from sebaceous follicles. Although commonly asymptomatic, these lesions can manifest with pruritus or become infected, predisposing patients to further complications.¹ Steatocystomas can manifest as single (steatocystoma simplex [SS]) or numerous (steatocystoma multiplex [SM]) lesions; the lesions also can spontaneously rupture with characteristics that resemble hidradenitis suppurativa (HS)(steatocystoma multiplex suppurativa [SMS]).^1,2

Steatocystomas are relatively rare, and there is limited consensus in the published literature on the etiology and management of this condition. In this article, we present a comprehensive review of steatocystomas in the current literature. We highlight important features to consider when making the diagnosis and also offer recommendations for best-practice treatment.

Historical Background

Although not explicitly identified by name, the first documentation of steatocystomas is a case report published in 1873. In this account, the author described a patient who presented with approximately 250 flesh-colored dermal cysts across the body that varied in size.³ In 1899, the term steatocystoma multiple—derived from Greek roots meaning “fatty bag”—was first used.⁴

In 1982, almost a century later, Brownstein⁵ reported some of the earliest cases of SS. This solitary subtype is identical to SM on a microscopic level; however, unlike SM, this variant occurs as a single lesion that typically forms in adulthood and in the absence of family history. Other benign adnexal tumors (eg, pilomatricomas, pilar cysts, and sebaceous hyperplasias) also can manifest as either solitary or multiple lesions.

In 1976, McDonald and Reed⁶ reported the first known cases of patients with both SM and HS. At the time, the co-occurrence of these conditions was viewed as coincidental, but there were postulations of a shared inflammatory process and hereditary link⁶; it was not until 1982 that the term steatocystoma multiplex suppurativum was coined to describe this variant.⁷ Although rare, there have been multiple documented instances of SMS since. It has been suggested that the convergence of these conditions may indicate a shared follicular proliferation defect.⁸ Ongoing investigation is warranted to explain the underlying pathogenesis of this unique variant.

Epidemiology

The available epidemiologic data primarily relate to SM, the most common steatocystoma variant. Nevertheless, SM is a relatively rare condition, and the exact incidence and prevalence remain unknown.^8,9 Steatocystomas typically manifest in the first and second decades of life and have been observed in patients of both sexes, with studies demonstrating no notable sex bias.^4,9

Etiology and Pathophysiology

Steatocystomas can occur sporadically or may be inherited as an autosomal-dominant condition.⁴ Typically, SS tends to manifest as an isolated occurrence without any inherent genetic predisposition.⁵ Alternatively, SM may develop sporadically or be associated with a mutation in the keratin 17 gene (KRT17).⁴ Steatocystoma multiplex also has been associated with at least 4 different missense mutations, including N92H, R94H, and R94C, located on the long (q) arm of chromosome 17.^4,10-12

The keratin 17 gene is responsible for encoding the keratin 17 protein, a type I intermediate filament predominantly synthesized in the basal cells of epithelial tissue. This fibrous structural protein can regulate many processes, including inflammation and cell proliferation, and is found in regions such as the sebaceous glands, hair follicles, and eccrine sweat glands. Overexpression of KRT17 has been suggested in other cutaneous conditions, most notably psoriasis.¹² Despite KRT17’s many roles, it remains unclear why SM typically manifests with a myriad of sebum-containing cysts as the primary symptom.¹² Continued investigation into the genetic underpinnings of SM and the keratin 17 protein is necessary to further elucidate a more comprehensive understanding of this condition.

Hormonal influences have been suggested as a potential trigger for steatocystoma growth.^4,13 This condition is associated with dysfunction of the sebaceous glands, and, correspondingly, the incidence of disease is highest in pubertal patients, in whom androgen levels and sebum production are elevated.^4,13,14 Two cases of transgender men taking testosterone therapy presenting with steatocystomas provide additional clinical support for this association.¹⁵

Additionally, the use of immunomodulatory agents, such as ustekinumab (anti–interleukin 12/interleukin 23), has been shown to trigger SM. It is predicted that the reduced expression of certain interferons and interleukins may lead to downstream consequences in the keratin 17 pathway and lead to SM lesion formation in genetically susceptible individuals.¹⁶ Targeting these potential causes in the future may prove efficacious in the secondary prevention of familial SM manifestation or exacerbations.

Mutations in the KRT17 gene also have been implicated in pachyonychia congenita type 2 (PC-2).⁴ Marked by extensive systemic hyperkeratosis, PC-2 has been observed to coincide with SM in certain patients.^4,5 Interestingly, the location of the KRT17 mutations are identical in both PC-2 and SM.⁴ Although most individuals with hereditary SM do not exhibit the characteristic features of PC-2, mild nail and dental abnormalities have been observed in some SM cases.^4,10 This relationship suggests that SM may be a less severe variant of PC-2 or part of a complex polygenetic spectrum of disease.¹⁰ Further research is imperative to determine the exact nature and extent of the relationship between these conditions.

Clinical Manifestations

Steatocystomas are flesh-colored subcutaneous cysts that range in size from less than 3 mm to larger than 3 cm in diameter (Figure). They form within a single pilosebaceous unit and typically display firm attachment due to their origination in the dermis.^2,7,17 Steatocystomas generally contain lipid material, and less frequently, keratin and hair shafts, distinguishing them as the only “true” sebaceous cysts.¹⁸ Their color can range from flesh-toned to yellow, with reports of occasional dark-blue shades and calcifications.^19,20 Steatocystomas can persist indefinitely, and they usually are asymptomatic.

Diagnosis of steatocystoma is confirmed by biopsy.⁴ Steatocystomas are characterized by a dermal cyst lined by stratified squamous cell epithelium (eFigures 1 and 2).²¹ Classically they feature flattened sebaceous lobules, multinucleated giant cells, and abortive hair follicles. The lining of these cysts is marked by lymphocytic infiltrate and a dense, wrinkled, eosinophilic keratin cuticle that replaces the granular layer.²² The cyst maintains an epidermal connection through a follicular infundibulum characterized by clumps of keratinocytes, sebocytes, corneocytes, and/or hair follicles.⁷ Aspirated contents reveal crystalline structures and anucleate squamous cells upon microscopic analysis. That being said, variable histologic findings of steatocystomas have been described.²³

Steatocystoma simplex, as the name implies, classifies a single isolated steatocystoma. This subtype exhibits similar histopathologic and clinical features to the other subtypes of steatocystomas. Notably, SS is not associated with a genetic mutation and is not an inherited condition within families.⁵ Steatocystoma multiplex manifests with many steatocystomas, often distributed widely across the body.^3,4 The chest, axillae, and groin are the most common locations; however, these cysts can manifest on the face, back, abdomen, and extremities.^4,18-22 Rare occurrences of SM limited to the face, scalp, and distal extremities have been documented.^18,21,24,25 Due to the possibility of an autosomal-dominant inheritance, it is advisable to take a comprehensive family history in patients for whom SM is in the differential.¹⁷

Steatocystoma multiplex—especially familial variants—has been shown to develop in conjunction with other dermatologic conditions, including eruptive vellus hair (EVH) cysts, persistent infantile milia, and epidermoid/dermoid cysts.²⁶ While some investigators regard these as separate entities due to their varied genetic etiology, it has been suggested that these conditions may be related and that the diagnosis is determined by the location of cyst origin along the sebaceous ducts.^26,27 Other dermatologic conditions and lesions that frequently manifest comorbidly with SM include hidrocystomas, syringomas, pilonidal cysts, lichen planus, nodulocystic acne, trichotillomania, trichoblastomas, trichoepithelioma, HS, keratoacanthomas, acrokeratosis verruciformis of Hopf, and embryonal hair formation. Steatocystoma multiplex, manifesting comorbidly with dental and orofacial malformations (eg, partial noneruption of secondary teeth, natal and defective teeth, and bilateral preauricular sinuses) has been classified as SM natal teeth syndrome.⁶

Steatocystoma multiplex suppurativa is a rare and serious variant of SM characterized by inflammation, cyst rupture, sinus tract formation, and scarring.²⁴ Patients with SMS typically have multiple intact SM cysts, which can aid in differentiation from HS.^2,24 Steatocystoma multiplex suppurativa is associated with more complications than SS and SM, including cyst perforation, development of purulent and/or foul-smelling discharge, infection, scarring, pain, and overall discomfort.²

Given its rarity and the potential manifestations that overlap with other conditions, steatocystomas easily can be misdiagnosed. In some clinical instances, EVHs may share similar characteristics with SM; however, certain distinguishing features exist, including a central tuft of protruding hairs and different expressed contents, such as the vellus hair shafts, from the cyst’s lumen.²⁸ Furthermore, histologic examination of EVHs reveals epidermoid keratinization of the lining as well as a lack of sebaceous glands within the wall.^28,29 Other similar conditions include epidermoid cysts, pilar cysts, lipomas, epidermal inclusion cysts, dermoid cysts, sebaceous hyperplasia, folliculitis, xanthomas, neurofibromatosis, and syringomas.³⁰ Occasionally, SMS can be mistaken for HS or acne conglobata, and SM lesions with a facial distribution can mimic acne vulgaris.^1,31 These conditions should be excluded before a diagnosis of SS, SM, or SMS is made. 

Importantly, SM is visually indistinguishable from subcutaneous metastasis on physical examination, and there are reports of oncologic conditions (eg, pulmonary adenocarcinoma metastasized to the skin) being mistaken for SS or SM.³² Therefore, a thorough clinical examination, histopathologic analysis, and potential use of other imaging modalities such as ultrasonography (US) are needed to ensure an accurate diagnosis.

Ultrasonography has demonstrated utility in diagnosing steatocystomas.^33-35 Steatocystomas have incidentally been found on routine mammograms and can demonstrate well-defined circular nodules with radiolucent characteristics and a thin radiodense outline.^33,36 Homogeneous hypoechoic nodules within the dermis without posterior acoustic features generally are observed (eFigure 3).^33,37 In patients declining biopsy, US may be useful in further characterization of an unknown lesion. Color Doppler US can be used to distinguish SMS from HS. Specifically, SM typically exhibits an absence of Doppler signaling due to a lack of vascularity, providing a helpful diagnostic clue for the SMS variant.³³

Management and Treatment Options

There is no established standard treatment for steatocystomas; therefore, the approach to management is contingent on clinical presentation and patient preferences. Various medical, surgical, and laser management options are available, each with its own advantages and limitations. Treatment of SM is difficult due to the large number of lesions.³⁸ In many cases, continued observation is a viable treatment option, as most SS and SM lesions are asymptomatic; however, cosmetic concerns can be debilitating for patients with SM and may warrant intervention.³⁹ More extensive medical and surgical management often are necessary in SMS due to associated morbidity. Discussing options and goals as well as setting realistic expectations with the patient are essential in determining the optimal approach.

Medical Management—In medical literature, oral isotretinoin (13-cis-retinoic acid) has been the mainstay of therapy for steatocystoma, as its effect on the size and activity of sebaceous glands is hypothesized to decrease disease activity.^38,40 Interventional studies and case reports have exhibited varying degrees of effectiveness.^1,38-41 Some reports depict a reduction in the formation of new lesions and a decrease in the size of pre-existing lesions, some show mild delayed therapeutic efficacy, and others suggest exacerbation of the condition.^1,38-41 This outcome variability is attributed to isotretinoin’s preferential efficacy in treating inflammatory lesions.^40,42

Tetracycline derivatives and intralesional steroid injections also have been employed with some efficacy in patients with focal inflammatory SM and SMS.⁴³ There is limited evidence on the long-term outcomes of these interventions, and intralesional injections often are not recommended in conditions such as SM, in which there are many lesions present.

Surgical Management—Minimally invasive surgical procedures including drainage and resections have been used with varying efficacy in SS and SM. Typically, a 2- to 3-mm incision or sharp-tipped cautery is employed to puncture the cyst. Alternatively, radiofrequency probes with a 2.4-MHz frequency setting have been used to minimize incision size.⁴⁴ The contents then are expressed with manual pressure or forceps, and the cyst sac is extracted using forceps and/or a vein hook (eFigure 4).^44,45 The specific surgical techniques and their respective advantages and limitations are summarized in the eTable. Reported advantages and limitations of surgical techniques are derived from information provided by the authors of steatocystoma case reports, which are based on observations of a very limited sample size.

Laser Treatment—Various laser modalities have been used in the management of steatocystomas, including carbon dioxide lasers, erbium-doped yttrium aluminum garnet lasers, 1450-nm diode plus 1550-nm fractionated erbium-doped fiber lasers, and 1927-nm diode lasers.^54,55-57 These lasers are used to perforate the cyst before extirpation and have displayed advantages in minimizing scar length.⁵⁸ The super-pulse mode of carbon dioxide lasers demonstrates efficacy with minimal scarring and recurrence, and this mode is preferred to minimize thermal damage.^54,59 Furthermore, this modality can be especially useful in patients whose condition is refractory to other noninvasive options.⁵⁹ Similarly, the erbium-doped yttrium aluminum garnet laser was well tolerated with no complications noted.⁵⁵ The 1927-nm diode laser also displayed good outcomes as well as no recurrence.⁵⁷ With laser use, it is important to note that multiple treatments are needed to see optimal outcomes.⁵⁴ Moreover, laser settings must be carefully considered, especially in patients with Fitzpatrick skin type III or higher, and topical anti-inflammatory agents should be considered posttreatment to minimize complications.^54,59,60

Recommendations

For management of SS, we recommend conservative therapy of watchful observation, as scarring or postinflammatory pigment change may be brought on by medical or surgical therapy; however, if SS is cosmetically bothersome, laser or surgical excision can be done (eFigure 4).^4,43-53 It is important to counsel the patient on risks/benefits. For SM, watchful observation also is indicated; however, systemic therapies aimed at prevention may be the most efficacious by limiting disease progression, and oral tetracycline or isotretinoin may be tried.⁴ Tetracyclines have the risk for photosensitivity and are teratogenic, while isotretinoin is extremely teratogenic, requires laboratory monitoring and regular pregnancy tests in women, and often causes substantial mucosal dryness. If lesions are bothersome or refractory to these therapies, intralesional steroids or surgical/laser procedures can be tried throughout multiple visits.^43-53 For SMS, systemic therapies frequently are recommended. The risks of systemic tetracycline and isotretinoin therapies must be discussed. Patients with treatment-refractory SMS may require surgical excision or deroofing of sinus tracts.^43-53 This management is similar to that of HS and must be tailored to the patient.

Conclusion

Overall, steatocystomas are a relatively rare pathology, with a limited consensus on their etiology and management. This review summarizes the current knowledge on the condition to support clinicians in diagnosis and management, ranging from watchful waiting to surgical removal. By individualizing treatment plans, clinicians ultimately can optimize outcomes in patients with steatocystomas.

Steatocystomas are small sebum-filled cysts that typically manifest in the dermis and originate from sebaceous follicles. Although commonly asymptomatic, these lesions can manifest with pruritus or become infected, predisposing patients to further complications.¹ Steatocystomas can manifest as single (steatocystoma simplex [SS]) or numerous (steatocystoma multiplex [SM]) lesions; the lesions also can spontaneously rupture with characteristics that resemble hidradenitis suppurativa (HS)(steatocystoma multiplex suppurativa [SMS]).^1,2

Steatocystomas are relatively rare, and there is limited consensus in the published literature on the etiology and management of this condition. In this article, we present a comprehensive review of steatocystomas in the current literature. We highlight important features to consider when making the diagnosis and also offer recommendations for best-practice treatment.

Historical Background

Although not explicitly identified by name, the first documentation of steatocystomas is a case report published in 1873. In this account, the author described a patient who presented with approximately 250 flesh-colored dermal cysts across the body that varied in size.³ In 1899, the term steatocystoma multiple—derived from Greek roots meaning “fatty bag”—was first used.⁴

In 1982, almost a century later, Brownstein⁵ reported some of the earliest cases of SS. This solitary subtype is identical to SM on a microscopic level; however, unlike SM, this variant occurs as a single lesion that typically forms in adulthood and in the absence of family history. Other benign adnexal tumors (eg, pilomatricomas, pilar cysts, and sebaceous hyperplasias) also can manifest as either solitary or multiple lesions.

In 1976, McDonald and Reed⁶ reported the first known cases of patients with both SM and HS. At the time, the co-occurrence of these conditions was viewed as coincidental, but there were postulations of a shared inflammatory process and hereditary link⁶; it was not until 1982 that the term steatocystoma multiplex suppurativum was coined to describe this variant.⁷ Although rare, there have been multiple documented instances of SMS since. It has been suggested that the convergence of these conditions may indicate a shared follicular proliferation defect.⁸ Ongoing investigation is warranted to explain the underlying pathogenesis of this unique variant.

Epidemiology

The available epidemiologic data primarily relate to SM, the most common steatocystoma variant. Nevertheless, SM is a relatively rare condition, and the exact incidence and prevalence remain unknown.^8,9 Steatocystomas typically manifest in the first and second decades of life and have been observed in patients of both sexes, with studies demonstrating no notable sex bias.^4,9

Etiology and Pathophysiology

Steatocystomas can occur sporadically or may be inherited as an autosomal-dominant condition.⁴ Typically, SS tends to manifest as an isolated occurrence without any inherent genetic predisposition.⁵ Alternatively, SM may develop sporadically or be associated with a mutation in the keratin 17 gene (KRT17).⁴ Steatocystoma multiplex also has been associated with at least 4 different missense mutations, including N92H, R94H, and R94C, located on the long (q) arm of chromosome 17.^4,10-12

The keratin 17 gene is responsible for encoding the keratin 17 protein, a type I intermediate filament predominantly synthesized in the basal cells of epithelial tissue. This fibrous structural protein can regulate many processes, including inflammation and cell proliferation, and is found in regions such as the sebaceous glands, hair follicles, and eccrine sweat glands. Overexpression of KRT17 has been suggested in other cutaneous conditions, most notably psoriasis.¹² Despite KRT17’s many roles, it remains unclear why SM typically manifests with a myriad of sebum-containing cysts as the primary symptom.¹² Continued investigation into the genetic underpinnings of SM and the keratin 17 protein is necessary to further elucidate a more comprehensive understanding of this condition.

Hormonal influences have been suggested as a potential trigger for steatocystoma growth.^4,13 This condition is associated with dysfunction of the sebaceous glands, and, correspondingly, the incidence of disease is highest in pubertal patients, in whom androgen levels and sebum production are elevated.^4,13,14 Two cases of transgender men taking testosterone therapy presenting with steatocystomas provide additional clinical support for this association.¹⁵

Additionally, the use of immunomodulatory agents, such as ustekinumab (anti–interleukin 12/interleukin 23), has been shown to trigger SM. It is predicted that the reduced expression of certain interferons and interleukins may lead to downstream consequences in the keratin 17 pathway and lead to SM lesion formation in genetically susceptible individuals.¹⁶ Targeting these potential causes in the future may prove efficacious in the secondary prevention of familial SM manifestation or exacerbations.

Mutations in the KRT17 gene also have been implicated in pachyonychia congenita type 2 (PC-2).⁴ Marked by extensive systemic hyperkeratosis, PC-2 has been observed to coincide with SM in certain patients.^4,5 Interestingly, the location of the KRT17 mutations are identical in both PC-2 and SM.⁴ Although most individuals with hereditary SM do not exhibit the characteristic features of PC-2, mild nail and dental abnormalities have been observed in some SM cases.^4,10 This relationship suggests that SM may be a less severe variant of PC-2 or part of a complex polygenetic spectrum of disease.¹⁰ Further research is imperative to determine the exact nature and extent of the relationship between these conditions.

Clinical Manifestations

Steatocystomas are flesh-colored subcutaneous cysts that range in size from less than 3 mm to larger than 3 cm in diameter (Figure). They form within a single pilosebaceous unit and typically display firm attachment due to their origination in the dermis.^2,7,17 Steatocystomas generally contain lipid material, and less frequently, keratin and hair shafts, distinguishing them as the only “true” sebaceous cysts.¹⁸ Their color can range from flesh-toned to yellow, with reports of occasional dark-blue shades and calcifications.^19,20 Steatocystomas can persist indefinitely, and they usually are asymptomatic.

Diagnosis of steatocystoma is confirmed by biopsy.⁴ Steatocystomas are characterized by a dermal cyst lined by stratified squamous cell epithelium (eFigures 1 and 2).²¹ Classically they feature flattened sebaceous lobules, multinucleated giant cells, and abortive hair follicles. The lining of these cysts is marked by lymphocytic infiltrate and a dense, wrinkled, eosinophilic keratin cuticle that replaces the granular layer.²² The cyst maintains an epidermal connection through a follicular infundibulum characterized by clumps of keratinocytes, sebocytes, corneocytes, and/or hair follicles.⁷ Aspirated contents reveal crystalline structures and anucleate squamous cells upon microscopic analysis. That being said, variable histologic findings of steatocystomas have been described.²³

Steatocystoma simplex, as the name implies, classifies a single isolated steatocystoma. This subtype exhibits similar histopathologic and clinical features to the other subtypes of steatocystomas. Notably, SS is not associated with a genetic mutation and is not an inherited condition within families.⁵ Steatocystoma multiplex manifests with many steatocystomas, often distributed widely across the body.^3,4 The chest, axillae, and groin are the most common locations; however, these cysts can manifest on the face, back, abdomen, and extremities.^4,18-22 Rare occurrences of SM limited to the face, scalp, and distal extremities have been documented.^18,21,24,25 Due to the possibility of an autosomal-dominant inheritance, it is advisable to take a comprehensive family history in patients for whom SM is in the differential.¹⁷

Steatocystoma multiplex—especially familial variants—has been shown to develop in conjunction with other dermatologic conditions, including eruptive vellus hair (EVH) cysts, persistent infantile milia, and epidermoid/dermoid cysts.²⁶ While some investigators regard these as separate entities due to their varied genetic etiology, it has been suggested that these conditions may be related and that the diagnosis is determined by the location of cyst origin along the sebaceous ducts.^26,27 Other dermatologic conditions and lesions that frequently manifest comorbidly with SM include hidrocystomas, syringomas, pilonidal cysts, lichen planus, nodulocystic acne, trichotillomania, trichoblastomas, trichoepithelioma, HS, keratoacanthomas, acrokeratosis verruciformis of Hopf, and embryonal hair formation. Steatocystoma multiplex, manifesting comorbidly with dental and orofacial malformations (eg, partial noneruption of secondary teeth, natal and defective teeth, and bilateral preauricular sinuses) has been classified as SM natal teeth syndrome.⁶

Steatocystoma multiplex suppurativa is a rare and serious variant of SM characterized by inflammation, cyst rupture, sinus tract formation, and scarring.²⁴ Patients with SMS typically have multiple intact SM cysts, which can aid in differentiation from HS.^2,24 Steatocystoma multiplex suppurativa is associated with more complications than SS and SM, including cyst perforation, development of purulent and/or foul-smelling discharge, infection, scarring, pain, and overall discomfort.²

Given its rarity and the potential manifestations that overlap with other conditions, steatocystomas easily can be misdiagnosed. In some clinical instances, EVHs may share similar characteristics with SM; however, certain distinguishing features exist, including a central tuft of protruding hairs and different expressed contents, such as the vellus hair shafts, from the cyst’s lumen.²⁸ Furthermore, histologic examination of EVHs reveals epidermoid keratinization of the lining as well as a lack of sebaceous glands within the wall.^28,29 Other similar conditions include epidermoid cysts, pilar cysts, lipomas, epidermal inclusion cysts, dermoid cysts, sebaceous hyperplasia, folliculitis, xanthomas, neurofibromatosis, and syringomas.³⁰ Occasionally, SMS can be mistaken for HS or acne conglobata, and SM lesions with a facial distribution can mimic acne vulgaris.^1,31 These conditions should be excluded before a diagnosis of SS, SM, or SMS is made. 

Importantly, SM is visually indistinguishable from subcutaneous metastasis on physical examination, and there are reports of oncologic conditions (eg, pulmonary adenocarcinoma metastasized to the skin) being mistaken for SS or SM.³² Therefore, a thorough clinical examination, histopathologic analysis, and potential use of other imaging modalities such as ultrasonography (US) are needed to ensure an accurate diagnosis.

Ultrasonography has demonstrated utility in diagnosing steatocystomas.^33-35 Steatocystomas have incidentally been found on routine mammograms and can demonstrate well-defined circular nodules with radiolucent characteristics and a thin radiodense outline.^33,36 Homogeneous hypoechoic nodules within the dermis without posterior acoustic features generally are observed (eFigure 3).^33,37 In patients declining biopsy, US may be useful in further characterization of an unknown lesion. Color Doppler US can be used to distinguish SMS from HS. Specifically, SM typically exhibits an absence of Doppler signaling due to a lack of vascularity, providing a helpful diagnostic clue for the SMS variant.³³

Management and Treatment Options

There is no established standard treatment for steatocystomas; therefore, the approach to management is contingent on clinical presentation and patient preferences. Various medical, surgical, and laser management options are available, each with its own advantages and limitations. Treatment of SM is difficult due to the large number of lesions.³⁸ In many cases, continued observation is a viable treatment option, as most SS and SM lesions are asymptomatic; however, cosmetic concerns can be debilitating for patients with SM and may warrant intervention.³⁹ More extensive medical and surgical management often are necessary in SMS due to associated morbidity. Discussing options and goals as well as setting realistic expectations with the patient are essential in determining the optimal approach.

Medical Management—In medical literature, oral isotretinoin (13-cis-retinoic acid) has been the mainstay of therapy for steatocystoma, as its effect on the size and activity of sebaceous glands is hypothesized to decrease disease activity.^38,40 Interventional studies and case reports have exhibited varying degrees of effectiveness.^1,38-41 Some reports depict a reduction in the formation of new lesions and a decrease in the size of pre-existing lesions, some show mild delayed therapeutic efficacy, and others suggest exacerbation of the condition.^1,38-41 This outcome variability is attributed to isotretinoin’s preferential efficacy in treating inflammatory lesions.^40,42

Tetracycline derivatives and intralesional steroid injections also have been employed with some efficacy in patients with focal inflammatory SM and SMS.⁴³ There is limited evidence on the long-term outcomes of these interventions, and intralesional injections often are not recommended in conditions such as SM, in which there are many lesions present.

Surgical Management—Minimally invasive surgical procedures including drainage and resections have been used with varying efficacy in SS and SM. Typically, a 2- to 3-mm incision or sharp-tipped cautery is employed to puncture the cyst. Alternatively, radiofrequency probes with a 2.4-MHz frequency setting have been used to minimize incision size.⁴⁴ The contents then are expressed with manual pressure or forceps, and the cyst sac is extracted using forceps and/or a vein hook (eFigure 4).^44,45 The specific surgical techniques and their respective advantages and limitations are summarized in the eTable. Reported advantages and limitations of surgical techniques are derived from information provided by the authors of steatocystoma case reports, which are based on observations of a very limited sample size.

Laser Treatment—Various laser modalities have been used in the management of steatocystomas, including carbon dioxide lasers, erbium-doped yttrium aluminum garnet lasers, 1450-nm diode plus 1550-nm fractionated erbium-doped fiber lasers, and 1927-nm diode lasers.^54,55-57 These lasers are used to perforate the cyst before extirpation and have displayed advantages in minimizing scar length.⁵⁸ The super-pulse mode of carbon dioxide lasers demonstrates efficacy with minimal scarring and recurrence, and this mode is preferred to minimize thermal damage.^54,59 Furthermore, this modality can be especially useful in patients whose condition is refractory to other noninvasive options.⁵⁹ Similarly, the erbium-doped yttrium aluminum garnet laser was well tolerated with no complications noted.⁵⁵ The 1927-nm diode laser also displayed good outcomes as well as no recurrence.⁵⁷ With laser use, it is important to note that multiple treatments are needed to see optimal outcomes.⁵⁴ Moreover, laser settings must be carefully considered, especially in patients with Fitzpatrick skin type III or higher, and topical anti-inflammatory agents should be considered posttreatment to minimize complications.^54,59,60

Recommendations

For management of SS, we recommend conservative therapy of watchful observation, as scarring or postinflammatory pigment change may be brought on by medical or surgical therapy; however, if SS is cosmetically bothersome, laser or surgical excision can be done (eFigure 4).^4,43-53 It is important to counsel the patient on risks/benefits. For SM, watchful observation also is indicated; however, systemic therapies aimed at prevention may be the most efficacious by limiting disease progression, and oral tetracycline or isotretinoin may be tried.⁴ Tetracyclines have the risk for photosensitivity and are teratogenic, while isotretinoin is extremely teratogenic, requires laboratory monitoring and regular pregnancy tests in women, and often causes substantial mucosal dryness. If lesions are bothersome or refractory to these therapies, intralesional steroids or surgical/laser procedures can be tried throughout multiple visits.^43-53 For SMS, systemic therapies frequently are recommended. The risks of systemic tetracycline and isotretinoin therapies must be discussed. Patients with treatment-refractory SMS may require surgical excision or deroofing of sinus tracts.^43-53 This management is similar to that of HS and must be tailored to the patient.

Conclusion

Overall, steatocystomas are a relatively rare pathology, with a limited consensus on their etiology and management. This review summarizes the current knowledge on the condition to support clinicians in diagnosis and management, ranging from watchful waiting to surgical removal. By individualizing treatment plans, clinicians ultimately can optimize outcomes in patients with steatocystomas.

Steatocystomas are small sebum-filled cysts that typically manifest in the dermis and originate from sebaceous follicles. Although commonly asymptomatic, these lesions can manifest with pruritus or become infected, predisposing patients to further complications.¹ Steatocystomas can manifest as single (steatocystoma simplex [SS]) or numerous (steatocystoma multiplex [SM]) lesions; the lesions also can spontaneously rupture with characteristics that resemble hidradenitis suppurativa (HS)(steatocystoma multiplex suppurativa [SMS]).^1,2

Steatocystomas are relatively rare, and there is limited consensus in the published literature on the etiology and management of this condition. In this article, we present a comprehensive review of steatocystomas in the current literature. We highlight important features to consider when making the diagnosis and also offer recommendations for best-practice treatment.

Historical Background

Although not explicitly identified by name, the first documentation of steatocystomas is a case report published in 1873. In this account, the author described a patient who presented with approximately 250 flesh-colored dermal cysts across the body that varied in size.³ In 1899, the term steatocystoma multiple—derived from Greek roots meaning “fatty bag”—was first used.⁴

In 1982, almost a century later, Brownstein⁵ reported some of the earliest cases of SS. This solitary subtype is identical to SM on a microscopic level; however, unlike SM, this variant occurs as a single lesion that typically forms in adulthood and in the absence of family history. Other benign adnexal tumors (eg, pilomatricomas, pilar cysts, and sebaceous hyperplasias) also can manifest as either solitary or multiple lesions.

In 1976, McDonald and Reed⁶ reported the first known cases of patients with both SM and HS. At the time, the co-occurrence of these conditions was viewed as coincidental, but there were postulations of a shared inflammatory process and hereditary link⁶; it was not until 1982 that the term steatocystoma multiplex suppurativum was coined to describe this variant.⁷ Although rare, there have been multiple documented instances of SMS since. It has been suggested that the convergence of these conditions may indicate a shared follicular proliferation defect.⁸ Ongoing investigation is warranted to explain the underlying pathogenesis of this unique variant.

Epidemiology

The available epidemiologic data primarily relate to SM, the most common steatocystoma variant. Nevertheless, SM is a relatively rare condition, and the exact incidence and prevalence remain unknown.^8,9 Steatocystomas typically manifest in the first and second decades of life and have been observed in patients of both sexes, with studies demonstrating no notable sex bias.^4,9

Etiology and Pathophysiology

Steatocystomas can occur sporadically or may be inherited as an autosomal-dominant condition.⁴ Typically, SS tends to manifest as an isolated occurrence without any inherent genetic predisposition.⁵ Alternatively, SM may develop sporadically or be associated with a mutation in the keratin 17 gene (KRT17).⁴ Steatocystoma multiplex also has been associated with at least 4 different missense mutations, including N92H, R94H, and R94C, located on the long (q) arm of chromosome 17.^4,10-12

The keratin 17 gene is responsible for encoding the keratin 17 protein, a type I intermediate filament predominantly synthesized in the basal cells of epithelial tissue. This fibrous structural protein can regulate many processes, including inflammation and cell proliferation, and is found in regions such as the sebaceous glands, hair follicles, and eccrine sweat glands. Overexpression of KRT17 has been suggested in other cutaneous conditions, most notably psoriasis.¹² Despite KRT17’s many roles, it remains unclear why SM typically manifests with a myriad of sebum-containing cysts as the primary symptom.¹² Continued investigation into the genetic underpinnings of SM and the keratin 17 protein is necessary to further elucidate a more comprehensive understanding of this condition.

Hormonal influences have been suggested as a potential trigger for steatocystoma growth.^4,13 This condition is associated with dysfunction of the sebaceous glands, and, correspondingly, the incidence of disease is highest in pubertal patients, in whom androgen levels and sebum production are elevated.^4,13,14 Two cases of transgender men taking testosterone therapy presenting with steatocystomas provide additional clinical support for this association.¹⁵

Additionally, the use of immunomodulatory agents, such as ustekinumab (anti–interleukin 12/interleukin 23), has been shown to trigger SM. It is predicted that the reduced expression of certain interferons and interleukins may lead to downstream consequences in the keratin 17 pathway and lead to SM lesion formation in genetically susceptible individuals.¹⁶ Targeting these potential causes in the future may prove efficacious in the secondary prevention of familial SM manifestation or exacerbations.

Mutations in the KRT17 gene also have been implicated in pachyonychia congenita type 2 (PC-2).⁴ Marked by extensive systemic hyperkeratosis, PC-2 has been observed to coincide with SM in certain patients.^4,5 Interestingly, the location of the KRT17 mutations are identical in both PC-2 and SM.⁴ Although most individuals with hereditary SM do not exhibit the characteristic features of PC-2, mild nail and dental abnormalities have been observed in some SM cases.^4,10 This relationship suggests that SM may be a less severe variant of PC-2 or part of a complex polygenetic spectrum of disease.¹⁰ Further research is imperative to determine the exact nature and extent of the relationship between these conditions.

Clinical Manifestations

Steatocystomas are flesh-colored subcutaneous cysts that range in size from less than 3 mm to larger than 3 cm in diameter (Figure). They form within a single pilosebaceous unit and typically display firm attachment due to their origination in the dermis.^2,7,17 Steatocystomas generally contain lipid material, and less frequently, keratin and hair shafts, distinguishing them as the only “true” sebaceous cysts.¹⁸ Their color can range from flesh-toned to yellow, with reports of occasional dark-blue shades and calcifications.^19,20 Steatocystomas can persist indefinitely, and they usually are asymptomatic.

Diagnosis of steatocystoma is confirmed by biopsy.⁴ Steatocystomas are characterized by a dermal cyst lined by stratified squamous cell epithelium (eFigures 1 and 2).²¹ Classically they feature flattened sebaceous lobules, multinucleated giant cells, and abortive hair follicles. The lining of these cysts is marked by lymphocytic infiltrate and a dense, wrinkled, eosinophilic keratin cuticle that replaces the granular layer.²² The cyst maintains an epidermal connection through a follicular infundibulum characterized by clumps of keratinocytes, sebocytes, corneocytes, and/or hair follicles.⁷ Aspirated contents reveal crystalline structures and anucleate squamous cells upon microscopic analysis. That being said, variable histologic findings of steatocystomas have been described.²³

Steatocystoma simplex, as the name implies, classifies a single isolated steatocystoma. This subtype exhibits similar histopathologic and clinical features to the other subtypes of steatocystomas. Notably, SS is not associated with a genetic mutation and is not an inherited condition within families.⁵ Steatocystoma multiplex manifests with many steatocystomas, often distributed widely across the body.^3,4 The chest, axillae, and groin are the most common locations; however, these cysts can manifest on the face, back, abdomen, and extremities.^4,18-22 Rare occurrences of SM limited to the face, scalp, and distal extremities have been documented.^18,21,24,25 Due to the possibility of an autosomal-dominant inheritance, it is advisable to take a comprehensive family history in patients for whom SM is in the differential.¹⁷

Steatocystoma multiplex—especially familial variants—has been shown to develop in conjunction with other dermatologic conditions, including eruptive vellus hair (EVH) cysts, persistent infantile milia, and epidermoid/dermoid cysts.²⁶ While some investigators regard these as separate entities due to their varied genetic etiology, it has been suggested that these conditions may be related and that the diagnosis is determined by the location of cyst origin along the sebaceous ducts.^26,27 Other dermatologic conditions and lesions that frequently manifest comorbidly with SM include hidrocystomas, syringomas, pilonidal cysts, lichen planus, nodulocystic acne, trichotillomania, trichoblastomas, trichoepithelioma, HS, keratoacanthomas, acrokeratosis verruciformis of Hopf, and embryonal hair formation. Steatocystoma multiplex, manifesting comorbidly with dental and orofacial malformations (eg, partial noneruption of secondary teeth, natal and defective teeth, and bilateral preauricular sinuses) has been classified as SM natal teeth syndrome.⁶

Steatocystoma multiplex suppurativa is a rare and serious variant of SM characterized by inflammation, cyst rupture, sinus tract formation, and scarring.²⁴ Patients with SMS typically have multiple intact SM cysts, which can aid in differentiation from HS.^2,24 Steatocystoma multiplex suppurativa is associated with more complications than SS and SM, including cyst perforation, development of purulent and/or foul-smelling discharge, infection, scarring, pain, and overall discomfort.²

Given its rarity and the potential manifestations that overlap with other conditions, steatocystomas easily can be misdiagnosed. In some clinical instances, EVHs may share similar characteristics with SM; however, certain distinguishing features exist, including a central tuft of protruding hairs and different expressed contents, such as the vellus hair shafts, from the cyst’s lumen.²⁸ Furthermore, histologic examination of EVHs reveals epidermoid keratinization of the lining as well as a lack of sebaceous glands within the wall.^28,29 Other similar conditions include epidermoid cysts, pilar cysts, lipomas, epidermal inclusion cysts, dermoid cysts, sebaceous hyperplasia, folliculitis, xanthomas, neurofibromatosis, and syringomas.³⁰ Occasionally, SMS can be mistaken for HS or acne conglobata, and SM lesions with a facial distribution can mimic acne vulgaris.^1,31 These conditions should be excluded before a diagnosis of SS, SM, or SMS is made. 

Importantly, SM is visually indistinguishable from subcutaneous metastasis on physical examination, and there are reports of oncologic conditions (eg, pulmonary adenocarcinoma metastasized to the skin) being mistaken for SS or SM.³² Therefore, a thorough clinical examination, histopathologic analysis, and potential use of other imaging modalities such as ultrasonography (US) are needed to ensure an accurate diagnosis.

Ultrasonography has demonstrated utility in diagnosing steatocystomas.^33-35 Steatocystomas have incidentally been found on routine mammograms and can demonstrate well-defined circular nodules with radiolucent characteristics and a thin radiodense outline.^33,36 Homogeneous hypoechoic nodules within the dermis without posterior acoustic features generally are observed (eFigure 3).^33,37 In patients declining biopsy, US may be useful in further characterization of an unknown lesion. Color Doppler US can be used to distinguish SMS from HS. Specifically, SM typically exhibits an absence of Doppler signaling due to a lack of vascularity, providing a helpful diagnostic clue for the SMS variant.³³

Management and Treatment Options

There is no established standard treatment for steatocystomas; therefore, the approach to management is contingent on clinical presentation and patient preferences. Various medical, surgical, and laser management options are available, each with its own advantages and limitations. Treatment of SM is difficult due to the large number of lesions.³⁸ In many cases, continued observation is a viable treatment option, as most SS and SM lesions are asymptomatic; however, cosmetic concerns can be debilitating for patients with SM and may warrant intervention.³⁹ More extensive medical and surgical management often are necessary in SMS due to associated morbidity. Discussing options and goals as well as setting realistic expectations with the patient are essential in determining the optimal approach.

Medical Management—In medical literature, oral isotretinoin (13-cis-retinoic acid) has been the mainstay of therapy for steatocystoma, as its effect on the size and activity of sebaceous glands is hypothesized to decrease disease activity.^38,40 Interventional studies and case reports have exhibited varying degrees of effectiveness.^1,38-41 Some reports depict a reduction in the formation of new lesions and a decrease in the size of pre-existing lesions, some show mild delayed therapeutic efficacy, and others suggest exacerbation of the condition.^1,38-41 This outcome variability is attributed to isotretinoin’s preferential efficacy in treating inflammatory lesions.^40,42

Tetracycline derivatives and intralesional steroid injections also have been employed with some efficacy in patients with focal inflammatory SM and SMS.⁴³ There is limited evidence on the long-term outcomes of these interventions, and intralesional injections often are not recommended in conditions such as SM, in which there are many lesions present.

Surgical Management—Minimally invasive surgical procedures including drainage and resections have been used with varying efficacy in SS and SM. Typically, a 2- to 3-mm incision or sharp-tipped cautery is employed to puncture the cyst. Alternatively, radiofrequency probes with a 2.4-MHz frequency setting have been used to minimize incision size.⁴⁴ The contents then are expressed with manual pressure or forceps, and the cyst sac is extracted using forceps and/or a vein hook (eFigure 4).^44,45 The specific surgical techniques and their respective advantages and limitations are summarized in the eTable. Reported advantages and limitations of surgical techniques are derived from information provided by the authors of steatocystoma case reports, which are based on observations of a very limited sample size.

Laser Treatment—Various laser modalities have been used in the management of steatocystomas, including carbon dioxide lasers, erbium-doped yttrium aluminum garnet lasers, 1450-nm diode plus 1550-nm fractionated erbium-doped fiber lasers, and 1927-nm diode lasers.^54,55-57 These lasers are used to perforate the cyst before extirpation and have displayed advantages in minimizing scar length.⁵⁸ The super-pulse mode of carbon dioxide lasers demonstrates efficacy with minimal scarring and recurrence, and this mode is preferred to minimize thermal damage.^54,59 Furthermore, this modality can be especially useful in patients whose condition is refractory to other noninvasive options.⁵⁹ Similarly, the erbium-doped yttrium aluminum garnet laser was well tolerated with no complications noted.⁵⁵ The 1927-nm diode laser also displayed good outcomes as well as no recurrence.⁵⁷ With laser use, it is important to note that multiple treatments are needed to see optimal outcomes.⁵⁴ Moreover, laser settings must be carefully considered, especially in patients with Fitzpatrick skin type III or higher, and topical anti-inflammatory agents should be considered posttreatment to minimize complications.^54,59,60

Recommendations

For management of SS, we recommend conservative therapy of watchful observation, as scarring or postinflammatory pigment change may be brought on by medical or surgical therapy; however, if SS is cosmetically bothersome, laser or surgical excision can be done (eFigure 4).^4,43-53 It is important to counsel the patient on risks/benefits. For SM, watchful observation also is indicated; however, systemic therapies aimed at prevention may be the most efficacious by limiting disease progression, and oral tetracycline or isotretinoin may be tried.⁴ Tetracyclines have the risk for photosensitivity and are teratogenic, while isotretinoin is extremely teratogenic, requires laboratory monitoring and regular pregnancy tests in women, and often causes substantial mucosal dryness. If lesions are bothersome or refractory to these therapies, intralesional steroids or surgical/laser procedures can be tried throughout multiple visits.^43-53 For SMS, systemic therapies frequently are recommended. The risks of systemic tetracycline and isotretinoin therapies must be discussed. Patients with treatment-refractory SMS may require surgical excision or deroofing of sinus tracts.^43-53 This management is similar to that of HS and must be tailored to the patient.

Conclusion

Overall, steatocystomas are a relatively rare pathology, with a limited consensus on their etiology and management. This review summarizes the current knowledge on the condition to support clinicians in diagnosis and management, ranging from watchful waiting to surgical removal. By individualizing treatment plans, clinicians ultimately can optimize outcomes in patients with steatocystomas.

Operational risk management (ORM) refers to the systematic identification and assessment of daily operational risks within an organization designed to mitigate negative financial, reputational, and safety outcomes while maximizing efficiency and achievement of objectives.¹ Operational risk management is indispensable to modern military operations, optimizing mission readiness while minimizing complications and personnel morbidity. Application of ORM in medicine holds considerable promise due to the emphasis on precise and efficient decision-making in high-stakes environments, where the margin for error is minimal. In this article, we propose integrating ORM principles into dermatologic surgery to enhance patient-centered care through improved counseling, risk assessment, and procedural outcomes. 

Principles and Processes of ORM

The ORM framework is built on 4 fundamental principles: accept risk when benefits outweigh the cost, accept no unnecessary risk, anticipate and manage risk by planning, and make risk decisions at the right level.² These principles form the foundation of the ORM’s systematic 5-step approach to identify hazards, assess hazards, make risk decisions, implement controls, and supervise. Key to the ORM process is the use of risk assessment codes and the risk assessment matrix to quantify and prioritize risks. Risk assessment codes are numerical values assigned to hazards based on their assessed severity and probability. The risk assessment matrix is a tool that plots the severity of a hazard against its probability. By locating a hazard on the matrix, users can visualize its risk level in terms of severity and probability. Building and using the risk assessment matrix begins with determining severity by assessing the potential impact of a hazard and categorizing it into levels (catastrophic, critical, moderate, or negligible). Next, probability is determined by evaluating the likelihood of occurrence (frequent, likely, occasional, seldom, or unlikely). Finally, the severity and probability are combined to assign a risk assessment code, which indicates the risk level and helps visualize criticality. Systematically applying these principles and processes enables users to make informed decisions that balance mission objectives with safety.

Proposed Framework for ORM in Dermatology Surgery

Current risk mitigation in dermatologic surgery includes strict medication oversight, sterilization protocols, and photography to prevent wrong-site surgeries. Preoperative risk assessment through conducting a thorough patient history is vital, considering factors such as pregnancy, allergies, bleeding history, cardiac devices, and keloid propensity, all of which impact surgical outcomes.^3-5 After gathering the patient’s history, dermatologists determine appropriateness for surgery and its inherent risks, typically via an informed consent process outlining the diagnosis and procedure purpose as well as a list of risks, benefits, and alternatives, including forgoing treatment.

Importantly, the standard process for dermatologic risk evaluation often lacks a comprehensive systematic approach seen in other higher-risk surgical fields. For example, general surgeons frequently utilize risk assessment calculators such as the one developed by the American College of Surgeons’ National Surgical Quality Improvement Program to estimate surgical complications.⁶ While specific guidelines exist for evaluating factors such as hypertension or anticoagulant use, no single tool synthesizes all patient risk factors for a unified assessment. Therefore, we propose integrating ORM as a structured decision-making process that offers a more consistent means for dermatologists to evaluate, synthesize, categorize, and present risks to patients. Our proposed process includes translating military mishap severity into a framework that helps patients better understand decisions about their health care when using ORM (eTable 1). The proposed process also provides dermatologists with a systematic, proactive, and iterative approach to assessing risks that allows them to consistently qualify medical decisions (eTable 2).

Patients often struggle to understand surgical risk severity, including overestimating the risks of routine minor procedures or underestimating the risks of more intensive procedures.^7,8 Incorporating ORM into patient communication mirrors the provider’s process but uses patient-friendly terminology—it is discussion based and integrates patient preferences and tolerances (eTable 2). These steps often occur informally in dermatologic counseling; however, an organized structured approach, especially using a visual aid such as a risk assessment matrix, enhances patient comprehension, recall, and satisfaction.⁹

Practical Scenarios 

Integrating ORM into dermatologic surgery is a proactive iterative process for both provider decision-making and patient communication. Leveraging a risk assessment matrix as a visual aid allows for clear identification, evaluation, and mitigation of hazards, fostering collaborative choices with regard to the treatment approach. Here we provide 2 case scenarios highlighting how ORM and the risk assessment matrix can be used in the management of a complex patient with a lesion in a high-risk location as well as to address patient anxiety and comorbidities. It is important to note that the way the matrices are completed in the examples provided may differ compared to other providers. The purpose of ORM is not to dictate risk categories but to serve as a tool for providers to take their own experiences and knowledge of the patient to guide their decision-making and counseling processes. 

Case Scenario 1—An elderly man with a history of diabetes, cardiovascular accident, coronary artery bypass grafting, and multiple squamous cell carcinoma excisions presents for evaluation of a 1-cm squamous cell carcinoma in situ on the left leg. His current medications include an anticoagulant and antihypertensives. 

In this scenario, the provider would apply ORM by identifying and assessing hazards, making risk decisions, implementing controls, and supervising care. 

General hazards for excision on the leg include bleeding, infection, scarring, pain, delayed healing, activity limitations, and possible further procedures. Before the visit, the provider should prepare baseline risk matrices for 2 potential treatment options: wide local excision and electrodessication and curettage. For example, surgical bleeding may be assessed as negligible severity and almost certain probability for a general excision.

Next, the provider would incorporate the patient’s unique history in the risk matrices (eFigures 1 and 2). The patient’s use of an anticoagulant indicates a bleeding risk; therefore, the provider may shift the severity to minimal clinical concern, understanding the need for enhanced perioperative management. The history of diabetes also has a considerable impact on wound healing, so the provider might elevate the probability of delayed wound healing from rare to unlikely and the severity from moderate to severe. The prior cardiovascular accident also raises concerns about mobility and activity limitations during recovery, which could be escalated from minimal to moderate clinical concern if postoperative limitations on ambulation increase the risk for new clots. Based on this internal assessment, the provider identifies which risks are elevated and require further attention and discussion with the patient, helping tailor the counseling approach and potential treatment plan. The provider should begin to consider initial control measures such as coordinating anticoagulant management, ensuring diabetes is well controlled, and planning for postoperative ambulation support.

Once the provider has conducted the internal assessment, the ORM matrices become powerful tools for shared decision-making with the patient. The provider can walk the patient through the procedures and their common risks and then explain how their individual situation modifies the risks. The visual and explicit upgrade on the matrices allows the patient to clearly see how unique factors influence their personal risk profile, moving beyond a generic list of complications. The provider then should engage the patient in a discussion about their risk tolerance, which is crucial for mutual agreement on whether to proceed with treatment and, if so, which procedure is most appropriate given the patient’s comfort level with their individualized risk profile. Then the provider should reinforce the proactive steps planned to mitigate the identified risks to provide assurance and reinforce the collaborative approach to safety. 

Finally, throughout the preoperative and postoperative phases, the provider should continuously monitor the patient’s condition and the effectiveness of the control measures, adjusting the plan as needed. 

In this scenario, both the provider and the patient participated in the risk assessment, with the provider completing the assessment before the visit and presenting it to the patient or performing the assessment in real time with the patient present to explain the reasoning behind assignment of risk based on each procedure and the patient’s unique risk factors. 

Case Scenario 2—A 38-year-old woman with a history of hypertension and procedural anxiety presents for evaluation of a biopsy-proven basal cell carcinoma on the nasal ala. The patient is taking diltiazem for hypertension and is compliant with her medication. Her blood pressure at the current visit is 148/96 mm Hg, which she attributes to white coat syndrome. Mohs micrographic surgery generally is the gold standard treatment for this case.

The provider’s ORM process, conducted either before or in real time during the visit, would begin with identification and assessment of the hazards. For Mohs surgery on the nasal ala, common hazards would include scarring, pain, infection, bleeding, and potential cosmetic distortion. Unique to this patient are the procedural anxiety and hypertension. 

To populate the risk assessment matrix (eFigure 3), the provider would first map the baseline risks of Mohs surgery, which include considerable scarring as a moderate clinical concern but a seldom probability. Because the patient’s procedural anxiety directly increases the probability of intraoperative distress or elevated blood pressure during the procedure, the provider might assess patient distress/anxiety as a moderate clinical concern with a likely probability. While the patient’s blood pressure is controlled, the white coat syndrome raises the probability of hypertensive urgency/emergency during surgery; this might be elevated from unlikely to occasional or likely probability, and severity might increase from minimal to moderate due to its potential impact on procedural safety. The provider should consider strategies to address these elevated risks during the consultation. Then, as part of preprocedure planning, the provider should consider discussing anxiolytics, emphasizing medication compliance, and ensuring a calm environment for the patient’s surgery.

For this patient, the risk assessment matrix becomes a powerful tool to address fears and proactively manage her unique risk factors. To start the counseling process, the provider should explain the procedure, its benefits, and potential adverse effects. Then, the patient’s individualized risks can be visualized using the matrix, which also is an opportunity for reassurance, as it can alleviate patient fears by contextualizing rare but impactful outcomes.⁹

Now the provider can assess the patient’s risk tolerance. This discussion ensures that the patient’s comfort level and preferences are central to the treatment decision, even for a gold-standard procedure such as Mohs surgery. By listening and responding to the patient’s input, the provider can build trust and discuss strategies that can help control for some risk factors.

Finally, the provider would re-evaluate throughout the procedure by continuously monitoring the patient’s anxiety and vital signs. The provider should also be ready to adjust pain management or employ anxiety-reduction techniques.

Final Thoughts

Reviewing the risk assessment matrix can be an effective way to nonjudgmentally discuss a patient’s unique risk factors and provide a complete understanding of the planned treatment or procedure. It conveys to the patient that, as the provider, you are taking their health seriously when considering treatment options and can be a means to build patient rapport and trust. This approach mirrors risk communication strategies long employed in military operational planning, where transparency and structured risk evaluation are essential to maintaining mission readiness and unit cohesion.

Operational risk management (ORM) refers to the systematic identification and assessment of daily operational risks within an organization designed to mitigate negative financial, reputational, and safety outcomes while maximizing efficiency and achievement of objectives.¹ Operational risk management is indispensable to modern military operations, optimizing mission readiness while minimizing complications and personnel morbidity. Application of ORM in medicine holds considerable promise due to the emphasis on precise and efficient decision-making in high-stakes environments, where the margin for error is minimal. In this article, we propose integrating ORM principles into dermatologic surgery to enhance patient-centered care through improved counseling, risk assessment, and procedural outcomes. 

Principles and Processes of ORM

The ORM framework is built on 4 fundamental principles: accept risk when benefits outweigh the cost, accept no unnecessary risk, anticipate and manage risk by planning, and make risk decisions at the right level.² These principles form the foundation of the ORM’s systematic 5-step approach to identify hazards, assess hazards, make risk decisions, implement controls, and supervise. Key to the ORM process is the use of risk assessment codes and the risk assessment matrix to quantify and prioritize risks. Risk assessment codes are numerical values assigned to hazards based on their assessed severity and probability. The risk assessment matrix is a tool that plots the severity of a hazard against its probability. By locating a hazard on the matrix, users can visualize its risk level in terms of severity and probability. Building and using the risk assessment matrix begins with determining severity by assessing the potential impact of a hazard and categorizing it into levels (catastrophic, critical, moderate, or negligible). Next, probability is determined by evaluating the likelihood of occurrence (frequent, likely, occasional, seldom, or unlikely). Finally, the severity and probability are combined to assign a risk assessment code, which indicates the risk level and helps visualize criticality. Systematically applying these principles and processes enables users to make informed decisions that balance mission objectives with safety.

Proposed Framework for ORM in Dermatology Surgery

Current risk mitigation in dermatologic surgery includes strict medication oversight, sterilization protocols, and photography to prevent wrong-site surgeries. Preoperative risk assessment through conducting a thorough patient history is vital, considering factors such as pregnancy, allergies, bleeding history, cardiac devices, and keloid propensity, all of which impact surgical outcomes.^3-5 After gathering the patient’s history, dermatologists determine appropriateness for surgery and its inherent risks, typically via an informed consent process outlining the diagnosis and procedure purpose as well as a list of risks, benefits, and alternatives, including forgoing treatment.

Importantly, the standard process for dermatologic risk evaluation often lacks a comprehensive systematic approach seen in other higher-risk surgical fields. For example, general surgeons frequently utilize risk assessment calculators such as the one developed by the American College of Surgeons’ National Surgical Quality Improvement Program to estimate surgical complications.⁶ While specific guidelines exist for evaluating factors such as hypertension or anticoagulant use, no single tool synthesizes all patient risk factors for a unified assessment. Therefore, we propose integrating ORM as a structured decision-making process that offers a more consistent means for dermatologists to evaluate, synthesize, categorize, and present risks to patients. Our proposed process includes translating military mishap severity into a framework that helps patients better understand decisions about their health care when using ORM (eTable 1). The proposed process also provides dermatologists with a systematic, proactive, and iterative approach to assessing risks that allows them to consistently qualify medical decisions (eTable 2).

Patients often struggle to understand surgical risk severity, including overestimating the risks of routine minor procedures or underestimating the risks of more intensive procedures.^7,8 Incorporating ORM into patient communication mirrors the provider’s process but uses patient-friendly terminology—it is discussion based and integrates patient preferences and tolerances (eTable 2). These steps often occur informally in dermatologic counseling; however, an organized structured approach, especially using a visual aid such as a risk assessment matrix, enhances patient comprehension, recall, and satisfaction.⁹

Practical Scenarios 

Integrating ORM into dermatologic surgery is a proactive iterative process for both provider decision-making and patient communication. Leveraging a risk assessment matrix as a visual aid allows for clear identification, evaluation, and mitigation of hazards, fostering collaborative choices with regard to the treatment approach. Here we provide 2 case scenarios highlighting how ORM and the risk assessment matrix can be used in the management of a complex patient with a lesion in a high-risk location as well as to address patient anxiety and comorbidities. It is important to note that the way the matrices are completed in the examples provided may differ compared to other providers. The purpose of ORM is not to dictate risk categories but to serve as a tool for providers to take their own experiences and knowledge of the patient to guide their decision-making and counseling processes. 

Case Scenario 1—An elderly man with a history of diabetes, cardiovascular accident, coronary artery bypass grafting, and multiple squamous cell carcinoma excisions presents for evaluation of a 1-cm squamous cell carcinoma in situ on the left leg. His current medications include an anticoagulant and antihypertensives. 

In this scenario, the provider would apply ORM by identifying and assessing hazards, making risk decisions, implementing controls, and supervising care. 

General hazards for excision on the leg include bleeding, infection, scarring, pain, delayed healing, activity limitations, and possible further procedures. Before the visit, the provider should prepare baseline risk matrices for 2 potential treatment options: wide local excision and electrodessication and curettage. For example, surgical bleeding may be assessed as negligible severity and almost certain probability for a general excision.

Next, the provider would incorporate the patient’s unique history in the risk matrices (eFigures 1 and 2). The patient’s use of an anticoagulant indicates a bleeding risk; therefore, the provider may shift the severity to minimal clinical concern, understanding the need for enhanced perioperative management. The history of diabetes also has a considerable impact on wound healing, so the provider might elevate the probability of delayed wound healing from rare to unlikely and the severity from moderate to severe. The prior cardiovascular accident also raises concerns about mobility and activity limitations during recovery, which could be escalated from minimal to moderate clinical concern if postoperative limitations on ambulation increase the risk for new clots. Based on this internal assessment, the provider identifies which risks are elevated and require further attention and discussion with the patient, helping tailor the counseling approach and potential treatment plan. The provider should begin to consider initial control measures such as coordinating anticoagulant management, ensuring diabetes is well controlled, and planning for postoperative ambulation support.

Once the provider has conducted the internal assessment, the ORM matrices become powerful tools for shared decision-making with the patient. The provider can walk the patient through the procedures and their common risks and then explain how their individual situation modifies the risks. The visual and explicit upgrade on the matrices allows the patient to clearly see how unique factors influence their personal risk profile, moving beyond a generic list of complications. The provider then should engage the patient in a discussion about their risk tolerance, which is crucial for mutual agreement on whether to proceed with treatment and, if so, which procedure is most appropriate given the patient’s comfort level with their individualized risk profile. Then the provider should reinforce the proactive steps planned to mitigate the identified risks to provide assurance and reinforce the collaborative approach to safety. 

Finally, throughout the preoperative and postoperative phases, the provider should continuously monitor the patient’s condition and the effectiveness of the control measures, adjusting the plan as needed. 

In this scenario, both the provider and the patient participated in the risk assessment, with the provider completing the assessment before the visit and presenting it to the patient or performing the assessment in real time with the patient present to explain the reasoning behind assignment of risk based on each procedure and the patient’s unique risk factors. 

Case Scenario 2—A 38-year-old woman with a history of hypertension and procedural anxiety presents for evaluation of a biopsy-proven basal cell carcinoma on the nasal ala. The patient is taking diltiazem for hypertension and is compliant with her medication. Her blood pressure at the current visit is 148/96 mm Hg, which she attributes to white coat syndrome. Mohs micrographic surgery generally is the gold standard treatment for this case.

The provider’s ORM process, conducted either before or in real time during the visit, would begin with identification and assessment of the hazards. For Mohs surgery on the nasal ala, common hazards would include scarring, pain, infection, bleeding, and potential cosmetic distortion. Unique to this patient are the procedural anxiety and hypertension. 

To populate the risk assessment matrix (eFigure 3), the provider would first map the baseline risks of Mohs surgery, which include considerable scarring as a moderate clinical concern but a seldom probability. Because the patient’s procedural anxiety directly increases the probability of intraoperative distress or elevated blood pressure during the procedure, the provider might assess patient distress/anxiety as a moderate clinical concern with a likely probability. While the patient’s blood pressure is controlled, the white coat syndrome raises the probability of hypertensive urgency/emergency during surgery; this might be elevated from unlikely to occasional or likely probability, and severity might increase from minimal to moderate due to its potential impact on procedural safety. The provider should consider strategies to address these elevated risks during the consultation. Then, as part of preprocedure planning, the provider should consider discussing anxiolytics, emphasizing medication compliance, and ensuring a calm environment for the patient’s surgery.

For this patient, the risk assessment matrix becomes a powerful tool to address fears and proactively manage her unique risk factors. To start the counseling process, the provider should explain the procedure, its benefits, and potential adverse effects. Then, the patient’s individualized risks can be visualized using the matrix, which also is an opportunity for reassurance, as it can alleviate patient fears by contextualizing rare but impactful outcomes.⁹

Now the provider can assess the patient’s risk tolerance. This discussion ensures that the patient’s comfort level and preferences are central to the treatment decision, even for a gold-standard procedure such as Mohs surgery. By listening and responding to the patient’s input, the provider can build trust and discuss strategies that can help control for some risk factors.

Finally, the provider would re-evaluate throughout the procedure by continuously monitoring the patient’s anxiety and vital signs. The provider should also be ready to adjust pain management or employ anxiety-reduction techniques.

Final Thoughts

Reviewing the risk assessment matrix can be an effective way to nonjudgmentally discuss a patient’s unique risk factors and provide a complete understanding of the planned treatment or procedure. It conveys to the patient that, as the provider, you are taking their health seriously when considering treatment options and can be a means to build patient rapport and trust. This approach mirrors risk communication strategies long employed in military operational planning, where transparency and structured risk evaluation are essential to maintaining mission readiness and unit cohesion.

Operational risk management (ORM) refers to the systematic identification and assessment of daily operational risks within an organization designed to mitigate negative financial, reputational, and safety outcomes while maximizing efficiency and achievement of objectives.¹ Operational risk management is indispensable to modern military operations, optimizing mission readiness while minimizing complications and personnel morbidity. Application of ORM in medicine holds considerable promise due to the emphasis on precise and efficient decision-making in high-stakes environments, where the margin for error is minimal. In this article, we propose integrating ORM principles into dermatologic surgery to enhance patient-centered care through improved counseling, risk assessment, and procedural outcomes. 

Principles and Processes of ORM

The ORM framework is built on 4 fundamental principles: accept risk when benefits outweigh the cost, accept no unnecessary risk, anticipate and manage risk by planning, and make risk decisions at the right level.² These principles form the foundation of the ORM’s systematic 5-step approach to identify hazards, assess hazards, make risk decisions, implement controls, and supervise. Key to the ORM process is the use of risk assessment codes and the risk assessment matrix to quantify and prioritize risks. Risk assessment codes are numerical values assigned to hazards based on their assessed severity and probability. The risk assessment matrix is a tool that plots the severity of a hazard against its probability. By locating a hazard on the matrix, users can visualize its risk level in terms of severity and probability. Building and using the risk assessment matrix begins with determining severity by assessing the potential impact of a hazard and categorizing it into levels (catastrophic, critical, moderate, or negligible). Next, probability is determined by evaluating the likelihood of occurrence (frequent, likely, occasional, seldom, or unlikely). Finally, the severity and probability are combined to assign a risk assessment code, which indicates the risk level and helps visualize criticality. Systematically applying these principles and processes enables users to make informed decisions that balance mission objectives with safety.

Proposed Framework for ORM in Dermatology Surgery

Current risk mitigation in dermatologic surgery includes strict medication oversight, sterilization protocols, and photography to prevent wrong-site surgeries. Preoperative risk assessment through conducting a thorough patient history is vital, considering factors such as pregnancy, allergies, bleeding history, cardiac devices, and keloid propensity, all of which impact surgical outcomes.^3-5 After gathering the patient’s history, dermatologists determine appropriateness for surgery and its inherent risks, typically via an informed consent process outlining the diagnosis and procedure purpose as well as a list of risks, benefits, and alternatives, including forgoing treatment.

Importantly, the standard process for dermatologic risk evaluation often lacks a comprehensive systematic approach seen in other higher-risk surgical fields. For example, general surgeons frequently utilize risk assessment calculators such as the one developed by the American College of Surgeons’ National Surgical Quality Improvement Program to estimate surgical complications.⁶ While specific guidelines exist for evaluating factors such as hypertension or anticoagulant use, no single tool synthesizes all patient risk factors for a unified assessment. Therefore, we propose integrating ORM as a structured decision-making process that offers a more consistent means for dermatologists to evaluate, synthesize, categorize, and present risks to patients. Our proposed process includes translating military mishap severity into a framework that helps patients better understand decisions about their health care when using ORM (eTable 1). The proposed process also provides dermatologists with a systematic, proactive, and iterative approach to assessing risks that allows them to consistently qualify medical decisions (eTable 2).

Patients often struggle to understand surgical risk severity, including overestimating the risks of routine minor procedures or underestimating the risks of more intensive procedures.^7,8 Incorporating ORM into patient communication mirrors the provider’s process but uses patient-friendly terminology—it is discussion based and integrates patient preferences and tolerances (eTable 2). These steps often occur informally in dermatologic counseling; however, an organized structured approach, especially using a visual aid such as a risk assessment matrix, enhances patient comprehension, recall, and satisfaction.⁹

Practical Scenarios 

Integrating ORM into dermatologic surgery is a proactive iterative process for both provider decision-making and patient communication. Leveraging a risk assessment matrix as a visual aid allows for clear identification, evaluation, and mitigation of hazards, fostering collaborative choices with regard to the treatment approach. Here we provide 2 case scenarios highlighting how ORM and the risk assessment matrix can be used in the management of a complex patient with a lesion in a high-risk location as well as to address patient anxiety and comorbidities. It is important to note that the way the matrices are completed in the examples provided may differ compared to other providers. The purpose of ORM is not to dictate risk categories but to serve as a tool for providers to take their own experiences and knowledge of the patient to guide their decision-making and counseling processes. 

Case Scenario 1—An elderly man with a history of diabetes, cardiovascular accident, coronary artery bypass grafting, and multiple squamous cell carcinoma excisions presents for evaluation of a 1-cm squamous cell carcinoma in situ on the left leg. His current medications include an anticoagulant and antihypertensives. 

In this scenario, the provider would apply ORM by identifying and assessing hazards, making risk decisions, implementing controls, and supervising care. 

General hazards for excision on the leg include bleeding, infection, scarring, pain, delayed healing, activity limitations, and possible further procedures. Before the visit, the provider should prepare baseline risk matrices for 2 potential treatment options: wide local excision and electrodessication and curettage. For example, surgical bleeding may be assessed as negligible severity and almost certain probability for a general excision.

Next, the provider would incorporate the patient’s unique history in the risk matrices (eFigures 1 and 2). The patient’s use of an anticoagulant indicates a bleeding risk; therefore, the provider may shift the severity to minimal clinical concern, understanding the need for enhanced perioperative management. The history of diabetes also has a considerable impact on wound healing, so the provider might elevate the probability of delayed wound healing from rare to unlikely and the severity from moderate to severe. The prior cardiovascular accident also raises concerns about mobility and activity limitations during recovery, which could be escalated from minimal to moderate clinical concern if postoperative limitations on ambulation increase the risk for new clots. Based on this internal assessment, the provider identifies which risks are elevated and require further attention and discussion with the patient, helping tailor the counseling approach and potential treatment plan. The provider should begin to consider initial control measures such as coordinating anticoagulant management, ensuring diabetes is well controlled, and planning for postoperative ambulation support.

Once the provider has conducted the internal assessment, the ORM matrices become powerful tools for shared decision-making with the patient. The provider can walk the patient through the procedures and their common risks and then explain how their individual situation modifies the risks. The visual and explicit upgrade on the matrices allows the patient to clearly see how unique factors influence their personal risk profile, moving beyond a generic list of complications. The provider then should engage the patient in a discussion about their risk tolerance, which is crucial for mutual agreement on whether to proceed with treatment and, if so, which procedure is most appropriate given the patient’s comfort level with their individualized risk profile. Then the provider should reinforce the proactive steps planned to mitigate the identified risks to provide assurance and reinforce the collaborative approach to safety. 

Finally, throughout the preoperative and postoperative phases, the provider should continuously monitor the patient’s condition and the effectiveness of the control measures, adjusting the plan as needed. 

In this scenario, both the provider and the patient participated in the risk assessment, with the provider completing the assessment before the visit and presenting it to the patient or performing the assessment in real time with the patient present to explain the reasoning behind assignment of risk based on each procedure and the patient’s unique risk factors. 

Case Scenario 2—A 38-year-old woman with a history of hypertension and procedural anxiety presents for evaluation of a biopsy-proven basal cell carcinoma on the nasal ala. The patient is taking diltiazem for hypertension and is compliant with her medication. Her blood pressure at the current visit is 148/96 mm Hg, which she attributes to white coat syndrome. Mohs micrographic surgery generally is the gold standard treatment for this case.

The provider’s ORM process, conducted either before or in real time during the visit, would begin with identification and assessment of the hazards. For Mohs surgery on the nasal ala, common hazards would include scarring, pain, infection, bleeding, and potential cosmetic distortion. Unique to this patient are the procedural anxiety and hypertension. 

To populate the risk assessment matrix (eFigure 3), the provider would first map the baseline risks of Mohs surgery, which include considerable scarring as a moderate clinical concern but a seldom probability. Because the patient’s procedural anxiety directly increases the probability of intraoperative distress or elevated blood pressure during the procedure, the provider might assess patient distress/anxiety as a moderate clinical concern with a likely probability. While the patient’s blood pressure is controlled, the white coat syndrome raises the probability of hypertensive urgency/emergency during surgery; this might be elevated from unlikely to occasional or likely probability, and severity might increase from minimal to moderate due to its potential impact on procedural safety. The provider should consider strategies to address these elevated risks during the consultation. Then, as part of preprocedure planning, the provider should consider discussing anxiolytics, emphasizing medication compliance, and ensuring a calm environment for the patient’s surgery.

For this patient, the risk assessment matrix becomes a powerful tool to address fears and proactively manage her unique risk factors. To start the counseling process, the provider should explain the procedure, its benefits, and potential adverse effects. Then, the patient’s individualized risks can be visualized using the matrix, which also is an opportunity for reassurance, as it can alleviate patient fears by contextualizing rare but impactful outcomes.⁹

Now the provider can assess the patient’s risk tolerance. This discussion ensures that the patient’s comfort level and preferences are central to the treatment decision, even for a gold-standard procedure such as Mohs surgery. By listening and responding to the patient’s input, the provider can build trust and discuss strategies that can help control for some risk factors.

Finally, the provider would re-evaluate throughout the procedure by continuously monitoring the patient’s anxiety and vital signs. The provider should also be ready to adjust pain management or employ anxiety-reduction techniques.

Final Thoughts

Reviewing the risk assessment matrix can be an effective way to nonjudgmentally discuss a patient’s unique risk factors and provide a complete understanding of the planned treatment or procedure. It conveys to the patient that, as the provider, you are taking their health seriously when considering treatment options and can be a means to build patient rapport and trust. This approach mirrors risk communication strategies long employed in military operational planning, where transparency and structured risk evaluation are essential to maintaining mission readiness and unit cohesion.

Biting midges, commonly known as no-see-ums, are true flies (order Diptera) and members of the Ceratopogonidae family. Regionally, they are known as punkies in the Northeast, pinyon gnats in the Southwest, moose flies in Canada, and sand gnats in Georgia, among other names.¹ There are 6206 species found worldwide except for Antarctica.² The 3 genera of greatest importance to human and livestock health in the United States are Culicoides, Leptoconops, and Forcipomyia.¹ Forty-seven species of the genus Culicoides are known to be present in Florida.³ Species belonging to the genus Leptoconops also are present in coastal areas of southeast Florida as well as in the tropics, subtropics, and Caribbean.³ In the United States, biting midges primarily are a nuisance; the major medical issue associated with Culicoides insects are allergic reactions to their bites. Even though no-see-ums are not known to transmit disease in humans, they have an impact on other animal species in the United States as biting pests and vectors of disease-causing pathogens.¹ Biting midges pose quite a nuisance for the proper enjoyment of outdoor spaces in the southeastern United States.

Characteristics

Morphologically, no-see-ums are gray flies measuring 1 to 3 mm in length (eFigure 1). Adults have 2 wings with distinctive patterns, large compound eyes, a thorax that extends slightly over the head, an abdomen with 9 segments, and antennae with 15 segments (eFigure 2).^1,3,4 Females have modified mouth parts including mandibles that lacerate the skin during feeding, which is mainly on blood from vertebrate hosts (primarily mammals but also birds, reptiles, and amphibians).^1,4 They also can feed on invertebrate hosts. Both male and female no-see-ums feed on nectar, but adult females require a blood meal to develop their eggs.² Their life cycle progresses in stages from egg to larva to pupa to adult. Larval habitats include salt marshes, swamps, shores of streams and ponds, water-holding plants, rotting fruit, and saturated wood- and manure-enriched soil. Adults can live 2 to 7 weeks. They are weak fliers, particularly in windy conditions.¹

In Florida, no-see-ums are more active during the rainy months of May to October but are active year-round in the southeastern United States and the Gulf Coast from Florida to West Texas. They are active throughout the United States in the warmer months of June and July.⁵ Their peak feeding activity occurs at dawn and dusk, but different species of biting midges such as Leptoconops and Culicoides also can feed during daylight hours and at night, respectively.^1,6,7

Case Report

One of the authors (M.J.S.), a healthy 54-year-old man with no remarkable medical history or current use of medications, documented the natural progression of a no-see-um bite by sitting in an outdoor Florida space at 8:00 am armed with a dermatoscope and a smartphone camera. The initial sensation of the bite felt like a sting that progressed over a few minutes to itchiness; however, the culprit was not readily identifiable. Upon closer inspection, pinpoint black dots could be correlated with the location of discomfort on the exposed upper extremities. Upon dermoscopic examination, 2 biting midges were identified as well as multiple wheals at the bite sites, and they seemed unbothered by the polarized light of the dermatoscope while feeding (eFigure 3). They flew away after a few minutes of feeding. The site of the bite wound was readily identifiable on dermoscopy as a wheal with a pinpoint red dot at the center (eFigure 4). The wheal started to form during the act of feeding and lasted up to 2 hours before fading (eFigure 5). The itch quickly resolved within the hour if hydrocortisone 1% was used. If untreated and scratched, itching rarely could last longer than a day.

Clinical Manifestations

Although no-see-ums are not known to transmit disease in the United States, they are important biting pests that can affect tourism and prevent enjoyment of outdoor spaces and activities.² The bite reactions on the host can range from wheal-like lesions to papules measuring 2 to 3 mm (at times with overlying vesicles) to nodules up to 1 cm in diameter.⁸ In our reported case, the small wheals disappeared within hours, but pruritic papules have been described to last from weeks to months. Published histopathologic correlation of biopsied indurated papules within 3 days of bite occurrence have revealed a superficial infiltrate composed of lymphocytes and histiocytes, while eosinophils were found in the deeper dermis and subcutaneous fat. Within 2 weeks, as the lesions aged, the infiltrate contained a smaller percentage of eosinophils and predominantly was present in only the superficial dermis.⁸ Delayed-type hypersensitivity reactions including pustules and bullous lesions also have been described.^9,10 Host immune reaction to the saliva introduced during the bite dictates the severity of the response, and lesions may become secondarily infected due to scratching.¹¹

Management Recommendations

Management consists of cleaning the bite site with soap and water to prevent infection, applying cold compresses or ice packs to relieve the intense itch, and avoiding scratching.¹¹ Application of over-the-counter calamine lotion or hydrocortisone cream can relieve itch, and mid- to high-potency topical corticosteroids also can be prescribed for 1 to 2 weeks for more intense bite reactions in conjunction with oral antihistamines. Topical or oral antibiotics may be indicated if redness and swelling progress at the bite site or if breaks in the skin become secondarily infected.

Final Thoughts

Because of the wide-ranging habitats of no-see-ums, eradication programs using insecticides have been inefficient or environmentally suboptimal. Emptying all standing water in outdoor spaces will reduce the number of no-see-ums. Avoidance of the outdoors at dawn and dusk when no-see-ums are most active is helpful, as well as protecting exposed skin by wearing long-sleeved shirts and long pants when outside. Insect repellents containing DEET (N-N-diethyl-meta-toluamide) or picaridin can offer additional protection on the remaining exposed skin. Oil of lemon eucalyptus, or active compound p-menthane-3,8-diol, has been shown to be effective against no-see-ums. Use of DEET should be avoided in children younger than 2 years and p-menthane-3,8-diol in those younger than 3 years. Picaridin is safe for use in children.¹² Citronella oil is ineffective. Installing window and patio screens with a mesh size less than 16 can prevent no-see-ums from passing through the netting but will restrict air flow.³ Turning off porch lights also is helpful, as no-see-ums are attracted to light sources.⁶ Since no-see-ums are weak flyers, setting ceiling or window fans at high speeds can minimize exposure; similarly, being outdoors on a windy day may decrease the likelihood of being bitten. Ultimately, the best remedy for a bite is to prevent them from happening.

Biting midges, commonly known as no-see-ums, are true flies (order Diptera) and members of the Ceratopogonidae family. Regionally, they are known as punkies in the Northeast, pinyon gnats in the Southwest, moose flies in Canada, and sand gnats in Georgia, among other names.¹ There are 6206 species found worldwide except for Antarctica.² The 3 genera of greatest importance to human and livestock health in the United States are Culicoides, Leptoconops, and Forcipomyia.¹ Forty-seven species of the genus Culicoides are known to be present in Florida.³ Species belonging to the genus Leptoconops also are present in coastal areas of southeast Florida as well as in the tropics, subtropics, and Caribbean.³ In the United States, biting midges primarily are a nuisance; the major medical issue associated with Culicoides insects are allergic reactions to their bites. Even though no-see-ums are not known to transmit disease in humans, they have an impact on other animal species in the United States as biting pests and vectors of disease-causing pathogens.¹ Biting midges pose quite a nuisance for the proper enjoyment of outdoor spaces in the southeastern United States.

Characteristics

Morphologically, no-see-ums are gray flies measuring 1 to 3 mm in length (eFigure 1). Adults have 2 wings with distinctive patterns, large compound eyes, a thorax that extends slightly over the head, an abdomen with 9 segments, and antennae with 15 segments (eFigure 2).^1,3,4 Females have modified mouth parts including mandibles that lacerate the skin during feeding, which is mainly on blood from vertebrate hosts (primarily mammals but also birds, reptiles, and amphibians).^1,4 They also can feed on invertebrate hosts. Both male and female no-see-ums feed on nectar, but adult females require a blood meal to develop their eggs.² Their life cycle progresses in stages from egg to larva to pupa to adult. Larval habitats include salt marshes, swamps, shores of streams and ponds, water-holding plants, rotting fruit, and saturated wood- and manure-enriched soil. Adults can live 2 to 7 weeks. They are weak fliers, particularly in windy conditions.¹

In Florida, no-see-ums are more active during the rainy months of May to October but are active year-round in the southeastern United States and the Gulf Coast from Florida to West Texas. They are active throughout the United States in the warmer months of June and July.⁵ Their peak feeding activity occurs at dawn and dusk, but different species of biting midges such as Leptoconops and Culicoides also can feed during daylight hours and at night, respectively.^1,6,7

Case Report

One of the authors (M.J.S.), a healthy 54-year-old man with no remarkable medical history or current use of medications, documented the natural progression of a no-see-um bite by sitting in an outdoor Florida space at 8:00 am armed with a dermatoscope and a smartphone camera. The initial sensation of the bite felt like a sting that progressed over a few minutes to itchiness; however, the culprit was not readily identifiable. Upon closer inspection, pinpoint black dots could be correlated with the location of discomfort on the exposed upper extremities. Upon dermoscopic examination, 2 biting midges were identified as well as multiple wheals at the bite sites, and they seemed unbothered by the polarized light of the dermatoscope while feeding (eFigure 3). They flew away after a few minutes of feeding. The site of the bite wound was readily identifiable on dermoscopy as a wheal with a pinpoint red dot at the center (eFigure 4). The wheal started to form during the act of feeding and lasted up to 2 hours before fading (eFigure 5). The itch quickly resolved within the hour if hydrocortisone 1% was used. If untreated and scratched, itching rarely could last longer than a day.

Clinical Manifestations

Although no-see-ums are not known to transmit disease in the United States, they are important biting pests that can affect tourism and prevent enjoyment of outdoor spaces and activities.² The bite reactions on the host can range from wheal-like lesions to papules measuring 2 to 3 mm (at times with overlying vesicles) to nodules up to 1 cm in diameter.⁸ In our reported case, the small wheals disappeared within hours, but pruritic papules have been described to last from weeks to months. Published histopathologic correlation of biopsied indurated papules within 3 days of bite occurrence have revealed a superficial infiltrate composed of lymphocytes and histiocytes, while eosinophils were found in the deeper dermis and subcutaneous fat. Within 2 weeks, as the lesions aged, the infiltrate contained a smaller percentage of eosinophils and predominantly was present in only the superficial dermis.⁸ Delayed-type hypersensitivity reactions including pustules and bullous lesions also have been described.^9,10 Host immune reaction to the saliva introduced during the bite dictates the severity of the response, and lesions may become secondarily infected due to scratching.¹¹

Management Recommendations

Management consists of cleaning the bite site with soap and water to prevent infection, applying cold compresses or ice packs to relieve the intense itch, and avoiding scratching.¹¹ Application of over-the-counter calamine lotion or hydrocortisone cream can relieve itch, and mid- to high-potency topical corticosteroids also can be prescribed for 1 to 2 weeks for more intense bite reactions in conjunction with oral antihistamines. Topical or oral antibiotics may be indicated if redness and swelling progress at the bite site or if breaks in the skin become secondarily infected.

Final Thoughts

Because of the wide-ranging habitats of no-see-ums, eradication programs using insecticides have been inefficient or environmentally suboptimal. Emptying all standing water in outdoor spaces will reduce the number of no-see-ums. Avoidance of the outdoors at dawn and dusk when no-see-ums are most active is helpful, as well as protecting exposed skin by wearing long-sleeved shirts and long pants when outside. Insect repellents containing DEET (N-N-diethyl-meta-toluamide) or picaridin can offer additional protection on the remaining exposed skin. Oil of lemon eucalyptus, or active compound p-menthane-3,8-diol, has been shown to be effective against no-see-ums. Use of DEET should be avoided in children younger than 2 years and p-menthane-3,8-diol in those younger than 3 years. Picaridin is safe for use in children.¹² Citronella oil is ineffective. Installing window and patio screens with a mesh size less than 16 can prevent no-see-ums from passing through the netting but will restrict air flow.³ Turning off porch lights also is helpful, as no-see-ums are attracted to light sources.⁶ Since no-see-ums are weak flyers, setting ceiling or window fans at high speeds can minimize exposure; similarly, being outdoors on a windy day may decrease the likelihood of being bitten. Ultimately, the best remedy for a bite is to prevent them from happening.

Biting midges, commonly known as no-see-ums, are true flies (order Diptera) and members of the Ceratopogonidae family. Regionally, they are known as punkies in the Northeast, pinyon gnats in the Southwest, moose flies in Canada, and sand gnats in Georgia, among other names.¹ There are 6206 species found worldwide except for Antarctica.² The 3 genera of greatest importance to human and livestock health in the United States are Culicoides, Leptoconops, and Forcipomyia.¹ Forty-seven species of the genus Culicoides are known to be present in Florida.³ Species belonging to the genus Leptoconops also are present in coastal areas of southeast Florida as well as in the tropics, subtropics, and Caribbean.³ In the United States, biting midges primarily are a nuisance; the major medical issue associated with Culicoides insects are allergic reactions to their bites. Even though no-see-ums are not known to transmit disease in humans, they have an impact on other animal species in the United States as biting pests and vectors of disease-causing pathogens.¹ Biting midges pose quite a nuisance for the proper enjoyment of outdoor spaces in the southeastern United States.

Characteristics

Morphologically, no-see-ums are gray flies measuring 1 to 3 mm in length (eFigure 1). Adults have 2 wings with distinctive patterns, large compound eyes, a thorax that extends slightly over the head, an abdomen with 9 segments, and antennae with 15 segments (eFigure 2).^1,3,4 Females have modified mouth parts including mandibles that lacerate the skin during feeding, which is mainly on blood from vertebrate hosts (primarily mammals but also birds, reptiles, and amphibians).^1,4 They also can feed on invertebrate hosts. Both male and female no-see-ums feed on nectar, but adult females require a blood meal to develop their eggs.² Their life cycle progresses in stages from egg to larva to pupa to adult. Larval habitats include salt marshes, swamps, shores of streams and ponds, water-holding plants, rotting fruit, and saturated wood- and manure-enriched soil. Adults can live 2 to 7 weeks. They are weak fliers, particularly in windy conditions.¹

In Florida, no-see-ums are more active during the rainy months of May to October but are active year-round in the southeastern United States and the Gulf Coast from Florida to West Texas. They are active throughout the United States in the warmer months of June and July.⁵ Their peak feeding activity occurs at dawn and dusk, but different species of biting midges such as Leptoconops and Culicoides also can feed during daylight hours and at night, respectively.^1,6,7

Case Report

One of the authors (M.J.S.), a healthy 54-year-old man with no remarkable medical history or current use of medications, documented the natural progression of a no-see-um bite by sitting in an outdoor Florida space at 8:00 am armed with a dermatoscope and a smartphone camera. The initial sensation of the bite felt like a sting that progressed over a few minutes to itchiness; however, the culprit was not readily identifiable. Upon closer inspection, pinpoint black dots could be correlated with the location of discomfort on the exposed upper extremities. Upon dermoscopic examination, 2 biting midges were identified as well as multiple wheals at the bite sites, and they seemed unbothered by the polarized light of the dermatoscope while feeding (eFigure 3). They flew away after a few minutes of feeding. The site of the bite wound was readily identifiable on dermoscopy as a wheal with a pinpoint red dot at the center (eFigure 4). The wheal started to form during the act of feeding and lasted up to 2 hours before fading (eFigure 5). The itch quickly resolved within the hour if hydrocortisone 1% was used. If untreated and scratched, itching rarely could last longer than a day.

Clinical Manifestations

Although no-see-ums are not known to transmit disease in the United States, they are important biting pests that can affect tourism and prevent enjoyment of outdoor spaces and activities.² The bite reactions on the host can range from wheal-like lesions to papules measuring 2 to 3 mm (at times with overlying vesicles) to nodules up to 1 cm in diameter.⁸ In our reported case, the small wheals disappeared within hours, but pruritic papules have been described to last from weeks to months. Published histopathologic correlation of biopsied indurated papules within 3 days of bite occurrence have revealed a superficial infiltrate composed of lymphocytes and histiocytes, while eosinophils were found in the deeper dermis and subcutaneous fat. Within 2 weeks, as the lesions aged, the infiltrate contained a smaller percentage of eosinophils and predominantly was present in only the superficial dermis.⁸ Delayed-type hypersensitivity reactions including pustules and bullous lesions also have been described.^9,10 Host immune reaction to the saliva introduced during the bite dictates the severity of the response, and lesions may become secondarily infected due to scratching.¹¹

Management Recommendations

Management consists of cleaning the bite site with soap and water to prevent infection, applying cold compresses or ice packs to relieve the intense itch, and avoiding scratching.¹¹ Application of over-the-counter calamine lotion or hydrocortisone cream can relieve itch, and mid- to high-potency topical corticosteroids also can be prescribed for 1 to 2 weeks for more intense bite reactions in conjunction with oral antihistamines. Topical or oral antibiotics may be indicated if redness and swelling progress at the bite site or if breaks in the skin become secondarily infected.

Final Thoughts

Because of the wide-ranging habitats of no-see-ums, eradication programs using insecticides have been inefficient or environmentally suboptimal. Emptying all standing water in outdoor spaces will reduce the number of no-see-ums. Avoidance of the outdoors at dawn and dusk when no-see-ums are most active is helpful, as well as protecting exposed skin by wearing long-sleeved shirts and long pants when outside. Insect repellents containing DEET (N-N-diethyl-meta-toluamide) or picaridin can offer additional protection on the remaining exposed skin. Oil of lemon eucalyptus, or active compound p-menthane-3,8-diol, has been shown to be effective against no-see-ums. Use of DEET should be avoided in children younger than 2 years and p-menthane-3,8-diol in those younger than 3 years. Picaridin is safe for use in children.¹² Citronella oil is ineffective. Installing window and patio screens with a mesh size less than 16 can prevent no-see-ums from passing through the netting but will restrict air flow.³ Turning off porch lights also is helpful, as no-see-ums are attracted to light sources.⁶ Since no-see-ums are weak flyers, setting ceiling or window fans at high speeds can minimize exposure; similarly, being outdoors on a windy day may decrease the likelihood of being bitten. Ultimately, the best remedy for a bite is to prevent them from happening.

THE DIAGNOSIS: Squamoid Eccrine Ductal Carcinoma

Immunohistochemical staining of the biopsy specimen showed neoplastic aggregates that were diffusely positive for pancytokeratin and strongly positive for cytokeratin (CK) 5/6. Epithelial membrane antigen (EMA) and CK7 also were positive, CAM 5.2 was partially positive, and carcinoembryonic antigen (CEA) was focally positive (periluminal); S100 was negative. Given the histologic findings of irregular infiltrative cords and stranding exhibiting ductal differentiation in a fibrotic stroma in combination with the staining pattern, a diagnosis of squamous eccrine ductal carcinoma (SEDC) was made.

Squamoid eccrine ductal carcinoma is a rare primary cutaneous tumor with aggressive features that can be confused both clinically and histologically with squamous cell carcinoma (SCC). Histologically, SEDC is a biphasic tumor. If a shallow histologic specimen is obtained, it may be indistinguishable from a well-differentiated SCC (Figure 1). A deeper biopsy reveals irregular infiltrative cords and strands exhibiting ductal differentiation in a fibrotic stroma.¹

The immunohistochemical staining pattern of SEDC is similar to that of SCC, showing diffuse staining with pancytokeratin (AE1/AE3), CK 5/6, CK7, p63, and EMA. What distinguishes SEDC from SCC is that CEA highlights areas of glandular differentiation. An additional histologic feature seen commonly with SEDC is perineural invasion.

The etiology of SEDC remains controversial; although it originally was considered an aggressive variant of SCC along the same continuum as adenosquamous carcinoma, the fifth edition of the WHO Classification of Skin Tumors² has categorized SEDC as an adnexal neoplasm. Our patient demonstrated an atypical presentation of this tumor, which has been most commonly described in the literature as manifesting on the head, neck, or upper extremities in older adults.³ Mohs micrographic surgery is the recommended treatment for this aggressive tumor.³

The differential diagnosis for SEDC includes microcystic adnexal carcinoma, porocarcinoma, and eccrine syringofibroadenoma. Microcystic adnexal carcinoma is a rare, low-grade tumor of the sweat glands that typically manifests as a firm pink papule or plaque in the head and neck region. Microscopically, it demonstrates cords of basaloid cells in a paisley-tie tadpole pattern with a dense pink to red stroma and horn cysts (Figure 2). Histologic differential diagnoses include syringoma, morpheaform basal cell carcinoma, desmoplastic trichoepithelioma, and trichoadenoma. Carcinoembryonic antigen stains positive in microcystic adnexal carcinoma, which helps distinguish it from basal cell carcinoma and SCC. Surgical excision or Mohs surgery are recommended for management.⁴

Porocarcinoma is a malignant skin tumor that originates from the intraepidermal sweat gland ducts. It also has been proposed that porocarcinoma develops from benign eccrine poroma. Porocarcinoma often is seen in elderly individuals, with a predilection for the lower extremities. Porocarcinoma demonstrates diverse clinical and histopathologic features, which can make diagnosis challenging. Histopathologically, porocarcinoma has an infiltrative growth pattern, with large basaloid epithelial cells that demonstrate ductal differentiation, cytologic atypia, increased mitotic activity, and tumor necrosis (Figure 3). Some porocarcinomas may exhibit squamous-cell, spindle-cell, or clear-cell differentiation. Neoplastic cells stain positive for CEA, EMA, and CD117, which can assist in distinguishing porocarcinoma from cutaneous SCC.⁵

Eccrine syringofibroadenoma is an unusual benign cutaneous adnexal tumor that manifests mostly in individuals aged 40 years or older. It develops as single or multiple lesions that usually affect the lower extremities. Histologically, eccrine syringofibroadenoma demonstrates unique findings of anastomosing ducts and monomorphous epithelial cells within a fibrovascular stroma (Figure 4). On immunohistochemistry, it stains positive for EMA, CEA, high-molecular-weight kininogen, and filaggrin.⁶ Periodic acid–Schiff staining also is positive.

THE DIAGNOSIS: Squamoid Eccrine Ductal Carcinoma

Immunohistochemical staining of the biopsy specimen showed neoplastic aggregates that were diffusely positive for pancytokeratin and strongly positive for cytokeratin (CK) 5/6. Epithelial membrane antigen (EMA) and CK7 also were positive, CAM 5.2 was partially positive, and carcinoembryonic antigen (CEA) was focally positive (periluminal); S100 was negative. Given the histologic findings of irregular infiltrative cords and stranding exhibiting ductal differentiation in a fibrotic stroma in combination with the staining pattern, a diagnosis of squamous eccrine ductal carcinoma (SEDC) was made.

Squamoid eccrine ductal carcinoma is a rare primary cutaneous tumor with aggressive features that can be confused both clinically and histologically with squamous cell carcinoma (SCC). Histologically, SEDC is a biphasic tumor. If a shallow histologic specimen is obtained, it may be indistinguishable from a well-differentiated SCC (Figure 1). A deeper biopsy reveals irregular infiltrative cords and strands exhibiting ductal differentiation in a fibrotic stroma.¹

The immunohistochemical staining pattern of SEDC is similar to that of SCC, showing diffuse staining with pancytokeratin (AE1/AE3), CK 5/6, CK7, p63, and EMA. What distinguishes SEDC from SCC is that CEA highlights areas of glandular differentiation. An additional histologic feature seen commonly with SEDC is perineural invasion.

The etiology of SEDC remains controversial; although it originally was considered an aggressive variant of SCC along the same continuum as adenosquamous carcinoma, the fifth edition of the WHO Classification of Skin Tumors² has categorized SEDC as an adnexal neoplasm. Our patient demonstrated an atypical presentation of this tumor, which has been most commonly described in the literature as manifesting on the head, neck, or upper extremities in older adults.³ Mohs micrographic surgery is the recommended treatment for this aggressive tumor.³

The differential diagnosis for SEDC includes microcystic adnexal carcinoma, porocarcinoma, and eccrine syringofibroadenoma. Microcystic adnexal carcinoma is a rare, low-grade tumor of the sweat glands that typically manifests as a firm pink papule or plaque in the head and neck region. Microscopically, it demonstrates cords of basaloid cells in a paisley-tie tadpole pattern with a dense pink to red stroma and horn cysts (Figure 2). Histologic differential diagnoses include syringoma, morpheaform basal cell carcinoma, desmoplastic trichoepithelioma, and trichoadenoma. Carcinoembryonic antigen stains positive in microcystic adnexal carcinoma, which helps distinguish it from basal cell carcinoma and SCC. Surgical excision or Mohs surgery are recommended for management.⁴

Porocarcinoma is a malignant skin tumor that originates from the intraepidermal sweat gland ducts. It also has been proposed that porocarcinoma develops from benign eccrine poroma. Porocarcinoma often is seen in elderly individuals, with a predilection for the lower extremities. Porocarcinoma demonstrates diverse clinical and histopathologic features, which can make diagnosis challenging. Histopathologically, porocarcinoma has an infiltrative growth pattern, with large basaloid epithelial cells that demonstrate ductal differentiation, cytologic atypia, increased mitotic activity, and tumor necrosis (Figure 3). Some porocarcinomas may exhibit squamous-cell, spindle-cell, or clear-cell differentiation. Neoplastic cells stain positive for CEA, EMA, and CD117, which can assist in distinguishing porocarcinoma from cutaneous SCC.⁵

Eccrine syringofibroadenoma is an unusual benign cutaneous adnexal tumor that manifests mostly in individuals aged 40 years or older. It develops as single or multiple lesions that usually affect the lower extremities. Histologically, eccrine syringofibroadenoma demonstrates unique findings of anastomosing ducts and monomorphous epithelial cells within a fibrovascular stroma (Figure 4). On immunohistochemistry, it stains positive for EMA, CEA, high-molecular-weight kininogen, and filaggrin.⁶ Periodic acid–Schiff staining also is positive.

THE DIAGNOSIS: Squamoid Eccrine Ductal Carcinoma

Immunohistochemical staining of the biopsy specimen showed neoplastic aggregates that were diffusely positive for pancytokeratin and strongly positive for cytokeratin (CK) 5/6. Epithelial membrane antigen (EMA) and CK7 also were positive, CAM 5.2 was partially positive, and carcinoembryonic antigen (CEA) was focally positive (periluminal); S100 was negative. Given the histologic findings of irregular infiltrative cords and stranding exhibiting ductal differentiation in a fibrotic stroma in combination with the staining pattern, a diagnosis of squamous eccrine ductal carcinoma (SEDC) was made.

Squamoid eccrine ductal carcinoma is a rare primary cutaneous tumor with aggressive features that can be confused both clinically and histologically with squamous cell carcinoma (SCC). Histologically, SEDC is a biphasic tumor. If a shallow histologic specimen is obtained, it may be indistinguishable from a well-differentiated SCC (Figure 1). A deeper biopsy reveals irregular infiltrative cords and strands exhibiting ductal differentiation in a fibrotic stroma.¹

The immunohistochemical staining pattern of SEDC is similar to that of SCC, showing diffuse staining with pancytokeratin (AE1/AE3), CK 5/6, CK7, p63, and EMA. What distinguishes SEDC from SCC is that CEA highlights areas of glandular differentiation. An additional histologic feature seen commonly with SEDC is perineural invasion.

The etiology of SEDC remains controversial; although it originally was considered an aggressive variant of SCC along the same continuum as adenosquamous carcinoma, the fifth edition of the WHO Classification of Skin Tumors² has categorized SEDC as an adnexal neoplasm. Our patient demonstrated an atypical presentation of this tumor, which has been most commonly described in the literature as manifesting on the head, neck, or upper extremities in older adults.³ Mohs micrographic surgery is the recommended treatment for this aggressive tumor.³

The differential diagnosis for SEDC includes microcystic adnexal carcinoma, porocarcinoma, and eccrine syringofibroadenoma. Microcystic adnexal carcinoma is a rare, low-grade tumor of the sweat glands that typically manifests as a firm pink papule or plaque in the head and neck region. Microscopically, it demonstrates cords of basaloid cells in a paisley-tie tadpole pattern with a dense pink to red stroma and horn cysts (Figure 2). Histologic differential diagnoses include syringoma, morpheaform basal cell carcinoma, desmoplastic trichoepithelioma, and trichoadenoma. Carcinoembryonic antigen stains positive in microcystic adnexal carcinoma, which helps distinguish it from basal cell carcinoma and SCC. Surgical excision or Mohs surgery are recommended for management.⁴

Porocarcinoma is a malignant skin tumor that originates from the intraepidermal sweat gland ducts. It also has been proposed that porocarcinoma develops from benign eccrine poroma. Porocarcinoma often is seen in elderly individuals, with a predilection for the lower extremities. Porocarcinoma demonstrates diverse clinical and histopathologic features, which can make diagnosis challenging. Histopathologically, porocarcinoma has an infiltrative growth pattern, with large basaloid epithelial cells that demonstrate ductal differentiation, cytologic atypia, increased mitotic activity, and tumor necrosis (Figure 3). Some porocarcinomas may exhibit squamous-cell, spindle-cell, or clear-cell differentiation. Neoplastic cells stain positive for CEA, EMA, and CD117, which can assist in distinguishing porocarcinoma from cutaneous SCC.⁵

Eccrine syringofibroadenoma is an unusual benign cutaneous adnexal tumor that manifests mostly in individuals aged 40 years or older. It develops as single or multiple lesions that usually affect the lower extremities. Histologically, eccrine syringofibroadenoma demonstrates unique findings of anastomosing ducts and monomorphous epithelial cells within a fibrovascular stroma (Figure 4). On immunohistochemistry, it stains positive for EMA, CEA, high-molecular-weight kininogen, and filaggrin.⁶ Periodic acid–Schiff staining also is positive.