Dermatopathology

The Diagnosis: Irritated Seborrheic Keratosis

Biopsies of one of the protruding papules and the underlying plaque were performed. The specimen from the papule showed hyperkeratosis, acanthosis, papillomatosis, and a flattened dermoepidermal junction with demarcated horizontal margin, which demonstrated apparent upward growth of the epidermis. Moderate lymphocytic infiltration in the upper dermis also was observed (Figure, A). The histologic findings of the plaque showed acanthosis, several pseudohorn cysts, hyperpigmentation of the basal layer, and a horizontal demarcation of the dermoepidermal junction (Figure, B).

Seborrheic keratosis is the most common benign epidermal tumor of the skin with variable appearance.¹ It usually begins with well-circumscribed, dull, flat, tan or brown patches that then grow into waxy verrucous papules.¹ There are many clinicopathologic variants of SK such as common SK, stucco keratosis, and dermatosis papulosa nigra in clinical variation, as well as acanthotic, hyperkeratotic, clonal, reticulated, irritated, and melanoacanthoma subtypes based on histological variation.^2,3

Seborrheic keratosis is a tumor of keratinocytic origin. Although genetics, sun exposure,⁴ and human papillomavirus infection⁵ are thought to be causative factors, the precise etiology of SK is unknown.¹

The histology of SK shows monotonous basaloid tumor cells without atypia. It generally is comprised of focal acanthosis and papillomatosis with a sharp flat base. Intraepithelial horn pseudocysts are notable features of SK and increased melanin often is seen.^2,6

Irritated SK is a histologic variant of SK that has been mechanically or chemically irritated or is involved in immunologic responses. Histologically, the dermis underlying an SK lesion filled with a dense lymphocytic infiltration is characteristic.^1,2

For symptomatic or cosmetically undesirable lesions, complete removal of the lesion is the preferred treatment. Cryotherapy, electrodesiccation followed by curettage, curettage followed by desiccation, laser ablation, and surgical excision are effective treatments.¹

The Diagnosis: Irritated Seborrheic Keratosis

Biopsies of one of the protruding papules and the underlying plaque were performed. The specimen from the papule showed hyperkeratosis, acanthosis, papillomatosis, and a flattened dermoepidermal junction with demarcated horizontal margin, which demonstrated apparent upward growth of the epidermis. Moderate lymphocytic infiltration in the upper dermis also was observed (Figure, A). The histologic findings of the plaque showed acanthosis, several pseudohorn cysts, hyperpigmentation of the basal layer, and a horizontal demarcation of the dermoepidermal junction (Figure, B).

Seborrheic keratosis is the most common benign epidermal tumor of the skin with variable appearance.¹ It usually begins with well-circumscribed, dull, flat, tan or brown patches that then grow into waxy verrucous papules.¹ There are many clinicopathologic variants of SK such as common SK, stucco keratosis, and dermatosis papulosa nigra in clinical variation, as well as acanthotic, hyperkeratotic, clonal, reticulated, irritated, and melanoacanthoma subtypes based on histological variation.^2,3

Seborrheic keratosis is a tumor of keratinocytic origin. Although genetics, sun exposure,⁴ and human papillomavirus infection⁵ are thought to be causative factors, the precise etiology of SK is unknown.¹

The histology of SK shows monotonous basaloid tumor cells without atypia. It generally is comprised of focal acanthosis and papillomatosis with a sharp flat base. Intraepithelial horn pseudocysts are notable features of SK and increased melanin often is seen.^2,6

Irritated SK is a histologic variant of SK that has been mechanically or chemically irritated or is involved in immunologic responses. Histologically, the dermis underlying an SK lesion filled with a dense lymphocytic infiltration is characteristic.^1,2

For symptomatic or cosmetically undesirable lesions, complete removal of the lesion is the preferred treatment. Cryotherapy, electrodesiccation followed by curettage, curettage followed by desiccation, laser ablation, and surgical excision are effective treatments.¹

The Diagnosis: Irritated Seborrheic Keratosis

Biopsies of one of the protruding papules and the underlying plaque were performed. The specimen from the papule showed hyperkeratosis, acanthosis, papillomatosis, and a flattened dermoepidermal junction with demarcated horizontal margin, which demonstrated apparent upward growth of the epidermis. Moderate lymphocytic infiltration in the upper dermis also was observed (Figure, A). The histologic findings of the plaque showed acanthosis, several pseudohorn cysts, hyperpigmentation of the basal layer, and a horizontal demarcation of the dermoepidermal junction (Figure, B).

Seborrheic keratosis is the most common benign epidermal tumor of the skin with variable appearance.¹ It usually begins with well-circumscribed, dull, flat, tan or brown patches that then grow into waxy verrucous papules.¹ There are many clinicopathologic variants of SK such as common SK, stucco keratosis, and dermatosis papulosa nigra in clinical variation, as well as acanthotic, hyperkeratotic, clonal, reticulated, irritated, and melanoacanthoma subtypes based on histological variation.^2,3

Seborrheic keratosis is a tumor of keratinocytic origin. Although genetics, sun exposure,⁴ and human papillomavirus infection⁵ are thought to be causative factors, the precise etiology of SK is unknown.¹

The histology of SK shows monotonous basaloid tumor cells without atypia. It generally is comprised of focal acanthosis and papillomatosis with a sharp flat base. Intraepithelial horn pseudocysts are notable features of SK and increased melanin often is seen.^2,6

Irritated SK is a histologic variant of SK that has been mechanically or chemically irritated or is involved in immunologic responses. Histologically, the dermis underlying an SK lesion filled with a dense lymphocytic infiltration is characteristic.^1,2

For symptomatic or cosmetically undesirable lesions, complete removal of the lesion is the preferred treatment. Cryotherapy, electrodesiccation followed by curettage, curettage followed by desiccation, laser ablation, and surgical excision are effective treatments.¹

Case Report

A 25-year-old woman with a 5-month history of severe lichen planus (LP) on the arms, legs, and trunk presented to the emergency department with generalized blisters and erythema over the entire body, including the face and soles, of 2 days’ duration. She was evaluated for the LP 1 week prior in a referral dermatology clinic, and in addition to topical corticosteroids, she received 1 injection of 40 mg intramuscular triamcinolone acetonide. Hours following the injection she developed nausea, vomiting, and fever. The patient reported that her last menstrual period was 3 weeks prior to the current presentation.

Physical examination revealed numerous lichenified, flat-topped, pink-violaceous, hyperpigmented, scaly papules and plaques (Figure 1), as well as tense, yellow, fluid-filled vesicles and bullae of various sizes on the neck, arms (Figure 2), legs, trunk, and dorsal aspect of the feet. The vesicles occurred on both normal skin and the lichenified plaques with a negative Nikolsky sign. There also were urticarial erythematous papules and plaques on the arms, trunk, neck, and face, some of which had vesicles or a violaceous dusky central hue (Figure 3). Vesicles were noted within both nostrils (nasal mucosa), and there were extremely tender erythematous patches and thick sheets of scales on the soles.

An elevated β human chorionic gonadotropin level and transvaginal ultrasonography confirmed an intrauterine pregnancy of 12 weeks’ gestation despite the patient’s report of the last menstrual period.

Histologic examination of a vesicle on the right arm revealed hyperkeratosis with hypergranulosis, vacuolar alteration of the basal layer with a paucicellular subepidermal vesicle, and melanophages in the superficial dermis consistent with vesicular LP (Figure 4). Histologic examination of an erythematous edematous plaque on the right upper leg revealed edema in the upper dermis with a perivascular and interstitial lymphocytic infiltrate with eosinophils. A third biopsy of a lichenoid flat-topped papule on the left arm revealed a mild bandlike infiltrate of lymphocytes and scattered eosinophils, eosinophilic colloid bodies and edema in the papillary dermis, and subepidermal vesicles and vacuolar alteration of the basal layer consistent with a vesicular lichenoid dermatitis (Figure 5). Direct immunofluorescence (DIF) of perilesional skin showed linear deposition of C3 and IgM along the basement membrane zone (BMZ) in addition to a shaggy pattern with cytoid bodies (Figure 6). There also was a faint linear deposit of IgA along the BMZ with cytoid bodies but negative for IgG. These results were interpreted as consistent with LP pemphigoides (LPP). Neither an enzyme-linked immunosorbent assay nor an immunoblot analysis was performed.

Because the patient was pregnant and had failed to respond to topical and intramuscular corticosteroids, she was started on intravenous methylprednisolone in the emergency department until new lesions stopped appearing. She was then discharged home on oral prednisone 50 mg (0.5 mg/kg/d), with close observation by her obstetrician. She also used clobetasol propionate ointment 0.05% for more severe lesions and triamcinolone acetonide cream 0.1% for less severe lesions until lesions resolved.

During treatment, the patient developed cellulitis on the leg that presented as pustules and erythema at a site of an eroded bulla, inframammary and axillary cutaneous candidiasis, and hyperglycemia at 19 weeks’ gestation. The cutaneous infections resolved with oral clindamycin 300 mg 3 times daily for 10 days. Topical mupirocin was used to treat the cellulitis and a mixture of zinc oxide, econazole cream, and desonide cream twice daily treated the candidiasis. Her obstetrician managed the hyperglycemia.

The bullous lesions and LP completely resolved after 2 months of treatment with oral prednisone 50 mg daily. The patient tolerated a corticosteroid taper (dose decreased by 5 mg every 2 weeks) until arriving at 10 mg, which was then decreased to 7.5 mg until delivery. A cesarean delivery was performed due to a large-for-gestational-age fetus, and an internist was consulted for the necessary precautions to increase the steroid dose during delivery due to the stress of the surgery and the risk for a hypothalamic crisis. There were no peripartum complications, and the baby was born without cutaneous lesions and remains healthy 1 year later. The patient remained disease free over 2 months postpartum, until new LP lesions developed without vesicles or bullae, which were then controlled with topical therapy. She was subsequently lost to follow-up.

Comment

Kaposi first described LPP in 1892 and used the term lichen ruber pemphigoides to describe a case of typical LP together with a widespread bullous eruption. Lichen planus pemphigoides is characterized by tense blisters that arise on lesions of LP as well as on skin unaffected by LP. In contrast, bullous LP blisters are confined to LP lesions only and occur from intense lichenoid inflammation and extensive liquefactive degeneration of basal keratinocytes. The vesicle formation in LPP is a result of autoantibodies to the bullous pemphigoid (BP) antigen BPAg2, which can be explained by the epitope spreading epiphenomenon whereby epidermotropic cytotoxic T cells damage the basal keratinocytes in LP by targeting unknown epidermal antigens, resulting in the exposure of BP180 and therefore instigating the autoimmune response.¹ The process of epitope spreading takes months to develop; the mean duration of LP before LPP is 8 weeks in children and 12 weeks in adults,² which is comparable to the current case.

Pathogenesis

Lichen planus pemphigoides usually is idiopathic; however, there have been cases reported in association with various medications including calcium channel blockers such as diltiazem, Chinese herbs,³ simvastatin,⁴ ramipril,^5,6 captopril,⁷ psoralen plus UVA phototherapy,⁸ and cinnarizine.⁹ In addition, in a case-controlled study, the use of neuroleptics or diuretics was found to be a risk factor for LPP development.¹⁰

This case is unique because it shows an association of LPP with an intrauterine pregnancy. Despite the fact that we did not perform the required studies to determine the exact cause, there probably exists an association between LPP and the pregnancy, as the patient presented with a 5-month history of severe LP prior to vesicle formation. The patient only developed the vesicular lesions during pregnancy, which were later controlled with systemic steroids and then recurred postpartum only as LP lesions, suggesting that the patient’s pregnancy may have contributed in the pathogenesis as an inducing factor. We suspect that the LP was aggravated by the pregnancy and continued to worsen, so much as to cause epitope spreading and lead to the bullous eruption at the end of the first trimester.²

Differential Diagnosis

Initially, we suspected a diagnosis of pemphigoid gestationis (PG), previously known as herpes gestationis. The classic presentation of PG starts with an intense pruritus followed by the emergence of pruritic urticarial papules and plaques in the umbilical or periumbilical areas. The lesions may become targetlike or polycyclic and may spread to other areas of the trunk, arms, and legs, often including the palms and soles.^11-15 Just as in our case, vesicles and bullous lesions appear at both the site of the urticarial plaques as well as on normal skin.16 The clinical features noted in our patient that were not typical of PG included the multiple lesions on the face and inside the nostrils. Only 20% of PG cases are associated with mucosal involvement,^11,12,15 and there are no documented reports of PG occurring in a patient with LP, according to a PubMed search of articles indexed for MEDLINE using the search terms pemphigoid gestationis, herpes gestationis, and lichen planus.

Lichen planus pemphigoides can be easily differentiated from BP. Lichen planus pemphigoides occurs in younger patients, with a mean age of 35 years, unlike BP, which commonly affects elderly men.¹⁷ Lichen planus pemphigoides also is less severe and has a better response to treatment than BP. It also affects the palms and soles, which are rarely affected in BP. There are no reports in the literature of BP developing during pregnancy, according to a PubMed search using the terms bullous pemphigoid and pregnancy. However, LPP and BP share a common antibody, the BP180 antigen, and differences exist in the epitope where the antibody binds in each condition.^18,19

Diagnosing LPP

In LPP, DIF typically shows linear deposits of IgG, IgM, IgA, fibrinogen, and C3 along the BMZ, of which IgG and C3 are most commonly seen.³ Our patient had linear deposition of C3, IgM, and IgA along the BMZ, which excluded bullous LP from the differential diagnosis. Bullous LP is not an autoimmune condition but rather is on the severe spectrum of LP where Max Joseph spaces become so large so as to lead to vesicle and bullae formation. In addition to the linear deposit at the BMZ, LPP typically reveals immunoglobulin (mainly IgM but also IgA), C3, and fibrinogen staining of colloid bodies in the papillary dermis on DIF; however, some cases of LPP only present with a linear deposition of C3 along the BMZ, which is why, similar to PG, these diagnoses by DIF are similar. Direct immunofluorescence of PG reveals linear IgG1 and IgG3 along the BMZ. IgG1 and IgG3 immunoglobulins are known to fix complement better than other immunoglobulins, thus linear C3 along the BMZ is the most consistently positive immunoreactant. Less common positive immunoreactivity with the same pattern has been seen with IgA, IgM, C1, and C4 (Table).^14,15,18 The lack of linear IgG and the presence of IgM is more suggestive of LPP.

The differential diagnosis of the subepidermal autoimmune blistering diseases associated with antibodies against BP180, including BP, LPP, and PG, often is challenging.¹⁵ However, LPP can now be distinguished by immunological studies including immunoblot analysis of the immunodominant region of NC16A of the BP180 antigen and the immunoglobulin subclass that reacts to 180-, 200-,²⁰ and 230-kDa antigens within the BMZ (Table).^15,18-20 The Table summarizes the different autoantibodies, antigens, and epitopes to distinguish subepidermal autoimmune blistering diseases.

Despite not performing these studies in our patient, we concluded that the clinical, histological, and DIF findings of this case are more consistent with LPP than with the other subepidermal blistering diseases. However, we cannot exclude the possibility of the patient having a new entity with a unique antibody from epitope spreading.

Conclusion

We present a case of lichenoid papules and plaques consistent with LP, with the development of vesicles and bullae after the first trimester of pregnancy. The clinical, pathologic, and DIF findings were highly suggestive of LPP. Although the exact pathogenic mechanism is not fully known, we suspect that pregnancy may have contributed to the origin of the disease. Further evaluation of pregnant patients with lichenoid lesions who develop blisters are needed for the elucidation of the mechanism, which may be secondary to epitope spreading that led to new autoantibody formation.

Case Report

A 25-year-old woman with a 5-month history of severe lichen planus (LP) on the arms, legs, and trunk presented to the emergency department with generalized blisters and erythema over the entire body, including the face and soles, of 2 days’ duration. She was evaluated for the LP 1 week prior in a referral dermatology clinic, and in addition to topical corticosteroids, she received 1 injection of 40 mg intramuscular triamcinolone acetonide. Hours following the injection she developed nausea, vomiting, and fever. The patient reported that her last menstrual period was 3 weeks prior to the current presentation.

Physical examination revealed numerous lichenified, flat-topped, pink-violaceous, hyperpigmented, scaly papules and plaques (Figure 1), as well as tense, yellow, fluid-filled vesicles and bullae of various sizes on the neck, arms (Figure 2), legs, trunk, and dorsal aspect of the feet. The vesicles occurred on both normal skin and the lichenified plaques with a negative Nikolsky sign. There also were urticarial erythematous papules and plaques on the arms, trunk, neck, and face, some of which had vesicles or a violaceous dusky central hue (Figure 3). Vesicles were noted within both nostrils (nasal mucosa), and there were extremely tender erythematous patches and thick sheets of scales on the soles.

An elevated β human chorionic gonadotropin level and transvaginal ultrasonography confirmed an intrauterine pregnancy of 12 weeks’ gestation despite the patient’s report of the last menstrual period.

Histologic examination of a vesicle on the right arm revealed hyperkeratosis with hypergranulosis, vacuolar alteration of the basal layer with a paucicellular subepidermal vesicle, and melanophages in the superficial dermis consistent with vesicular LP (Figure 4). Histologic examination of an erythematous edematous plaque on the right upper leg revealed edema in the upper dermis with a perivascular and interstitial lymphocytic infiltrate with eosinophils. A third biopsy of a lichenoid flat-topped papule on the left arm revealed a mild bandlike infiltrate of lymphocytes and scattered eosinophils, eosinophilic colloid bodies and edema in the papillary dermis, and subepidermal vesicles and vacuolar alteration of the basal layer consistent with a vesicular lichenoid dermatitis (Figure 5). Direct immunofluorescence (DIF) of perilesional skin showed linear deposition of C3 and IgM along the basement membrane zone (BMZ) in addition to a shaggy pattern with cytoid bodies (Figure 6). There also was a faint linear deposit of IgA along the BMZ with cytoid bodies but negative for IgG. These results were interpreted as consistent with LP pemphigoides (LPP). Neither an enzyme-linked immunosorbent assay nor an immunoblot analysis was performed.

Because the patient was pregnant and had failed to respond to topical and intramuscular corticosteroids, she was started on intravenous methylprednisolone in the emergency department until new lesions stopped appearing. She was then discharged home on oral prednisone 50 mg (0.5 mg/kg/d), with close observation by her obstetrician. She also used clobetasol propionate ointment 0.05% for more severe lesions and triamcinolone acetonide cream 0.1% for less severe lesions until lesions resolved.

During treatment, the patient developed cellulitis on the leg that presented as pustules and erythema at a site of an eroded bulla, inframammary and axillary cutaneous candidiasis, and hyperglycemia at 19 weeks’ gestation. The cutaneous infections resolved with oral clindamycin 300 mg 3 times daily for 10 days. Topical mupirocin was used to treat the cellulitis and a mixture of zinc oxide, econazole cream, and desonide cream twice daily treated the candidiasis. Her obstetrician managed the hyperglycemia.

The bullous lesions and LP completely resolved after 2 months of treatment with oral prednisone 50 mg daily. The patient tolerated a corticosteroid taper (dose decreased by 5 mg every 2 weeks) until arriving at 10 mg, which was then decreased to 7.5 mg until delivery. A cesarean delivery was performed due to a large-for-gestational-age fetus, and an internist was consulted for the necessary precautions to increase the steroid dose during delivery due to the stress of the surgery and the risk for a hypothalamic crisis. There were no peripartum complications, and the baby was born without cutaneous lesions and remains healthy 1 year later. The patient remained disease free over 2 months postpartum, until new LP lesions developed without vesicles or bullae, which were then controlled with topical therapy. She was subsequently lost to follow-up.

Comment

Kaposi first described LPP in 1892 and used the term lichen ruber pemphigoides to describe a case of typical LP together with a widespread bullous eruption. Lichen planus pemphigoides is characterized by tense blisters that arise on lesions of LP as well as on skin unaffected by LP. In contrast, bullous LP blisters are confined to LP lesions only and occur from intense lichenoid inflammation and extensive liquefactive degeneration of basal keratinocytes. The vesicle formation in LPP is a result of autoantibodies to the bullous pemphigoid (BP) antigen BPAg2, which can be explained by the epitope spreading epiphenomenon whereby epidermotropic cytotoxic T cells damage the basal keratinocytes in LP by targeting unknown epidermal antigens, resulting in the exposure of BP180 and therefore instigating the autoimmune response.¹ The process of epitope spreading takes months to develop; the mean duration of LP before LPP is 8 weeks in children and 12 weeks in adults,² which is comparable to the current case.

Pathogenesis

Lichen planus pemphigoides usually is idiopathic; however, there have been cases reported in association with various medications including calcium channel blockers such as diltiazem, Chinese herbs,³ simvastatin,⁴ ramipril,^5,6 captopril,⁷ psoralen plus UVA phototherapy,⁸ and cinnarizine.⁹ In addition, in a case-controlled study, the use of neuroleptics or diuretics was found to be a risk factor for LPP development.¹⁰

This case is unique because it shows an association of LPP with an intrauterine pregnancy. Despite the fact that we did not perform the required studies to determine the exact cause, there probably exists an association between LPP and the pregnancy, as the patient presented with a 5-month history of severe LP prior to vesicle formation. The patient only developed the vesicular lesions during pregnancy, which were later controlled with systemic steroids and then recurred postpartum only as LP lesions, suggesting that the patient’s pregnancy may have contributed in the pathogenesis as an inducing factor. We suspect that the LP was aggravated by the pregnancy and continued to worsen, so much as to cause epitope spreading and lead to the bullous eruption at the end of the first trimester.²

Differential Diagnosis

Initially, we suspected a diagnosis of pemphigoid gestationis (PG), previously known as herpes gestationis. The classic presentation of PG starts with an intense pruritus followed by the emergence of pruritic urticarial papules and plaques in the umbilical or periumbilical areas. The lesions may become targetlike or polycyclic and may spread to other areas of the trunk, arms, and legs, often including the palms and soles.^11-15 Just as in our case, vesicles and bullous lesions appear at both the site of the urticarial plaques as well as on normal skin.16 The clinical features noted in our patient that were not typical of PG included the multiple lesions on the face and inside the nostrils. Only 20% of PG cases are associated with mucosal involvement,^11,12,15 and there are no documented reports of PG occurring in a patient with LP, according to a PubMed search of articles indexed for MEDLINE using the search terms pemphigoid gestationis, herpes gestationis, and lichen planus.

Lichen planus pemphigoides can be easily differentiated from BP. Lichen planus pemphigoides occurs in younger patients, with a mean age of 35 years, unlike BP, which commonly affects elderly men.¹⁷ Lichen planus pemphigoides also is less severe and has a better response to treatment than BP. It also affects the palms and soles, which are rarely affected in BP. There are no reports in the literature of BP developing during pregnancy, according to a PubMed search using the terms bullous pemphigoid and pregnancy. However, LPP and BP share a common antibody, the BP180 antigen, and differences exist in the epitope where the antibody binds in each condition.^18,19

Diagnosing LPP

In LPP, DIF typically shows linear deposits of IgG, IgM, IgA, fibrinogen, and C3 along the BMZ, of which IgG and C3 are most commonly seen.³ Our patient had linear deposition of C3, IgM, and IgA along the BMZ, which excluded bullous LP from the differential diagnosis. Bullous LP is not an autoimmune condition but rather is on the severe spectrum of LP where Max Joseph spaces become so large so as to lead to vesicle and bullae formation. In addition to the linear deposit at the BMZ, LPP typically reveals immunoglobulin (mainly IgM but also IgA), C3, and fibrinogen staining of colloid bodies in the papillary dermis on DIF; however, some cases of LPP only present with a linear deposition of C3 along the BMZ, which is why, similar to PG, these diagnoses by DIF are similar. Direct immunofluorescence of PG reveals linear IgG1 and IgG3 along the BMZ. IgG1 and IgG3 immunoglobulins are known to fix complement better than other immunoglobulins, thus linear C3 along the BMZ is the most consistently positive immunoreactant. Less common positive immunoreactivity with the same pattern has been seen with IgA, IgM, C1, and C4 (Table).^14,15,18 The lack of linear IgG and the presence of IgM is more suggestive of LPP.

The differential diagnosis of the subepidermal autoimmune blistering diseases associated with antibodies against BP180, including BP, LPP, and PG, often is challenging.¹⁵ However, LPP can now be distinguished by immunological studies including immunoblot analysis of the immunodominant region of NC16A of the BP180 antigen and the immunoglobulin subclass that reacts to 180-, 200-,²⁰ and 230-kDa antigens within the BMZ (Table).^15,18-20 The Table summarizes the different autoantibodies, antigens, and epitopes to distinguish subepidermal autoimmune blistering diseases.

Despite not performing these studies in our patient, we concluded that the clinical, histological, and DIF findings of this case are more consistent with LPP than with the other subepidermal blistering diseases. However, we cannot exclude the possibility of the patient having a new entity with a unique antibody from epitope spreading.

Conclusion

We present a case of lichenoid papules and plaques consistent with LP, with the development of vesicles and bullae after the first trimester of pregnancy. The clinical, pathologic, and DIF findings were highly suggestive of LPP. Although the exact pathogenic mechanism is not fully known, we suspect that pregnancy may have contributed to the origin of the disease. Further evaluation of pregnant patients with lichenoid lesions who develop blisters are needed for the elucidation of the mechanism, which may be secondary to epitope spreading that led to new autoantibody formation.

Case Report

A 25-year-old woman with a 5-month history of severe lichen planus (LP) on the arms, legs, and trunk presented to the emergency department with generalized blisters and erythema over the entire body, including the face and soles, of 2 days’ duration. She was evaluated for the LP 1 week prior in a referral dermatology clinic, and in addition to topical corticosteroids, she received 1 injection of 40 mg intramuscular triamcinolone acetonide. Hours following the injection she developed nausea, vomiting, and fever. The patient reported that her last menstrual period was 3 weeks prior to the current presentation.

Physical examination revealed numerous lichenified, flat-topped, pink-violaceous, hyperpigmented, scaly papules and plaques (Figure 1), as well as tense, yellow, fluid-filled vesicles and bullae of various sizes on the neck, arms (Figure 2), legs, trunk, and dorsal aspect of the feet. The vesicles occurred on both normal skin and the lichenified plaques with a negative Nikolsky sign. There also were urticarial erythematous papules and plaques on the arms, trunk, neck, and face, some of which had vesicles or a violaceous dusky central hue (Figure 3). Vesicles were noted within both nostrils (nasal mucosa), and there were extremely tender erythematous patches and thick sheets of scales on the soles.

An elevated β human chorionic gonadotropin level and transvaginal ultrasonography confirmed an intrauterine pregnancy of 12 weeks’ gestation despite the patient’s report of the last menstrual period.

Histologic examination of a vesicle on the right arm revealed hyperkeratosis with hypergranulosis, vacuolar alteration of the basal layer with a paucicellular subepidermal vesicle, and melanophages in the superficial dermis consistent with vesicular LP (Figure 4). Histologic examination of an erythematous edematous plaque on the right upper leg revealed edema in the upper dermis with a perivascular and interstitial lymphocytic infiltrate with eosinophils. A third biopsy of a lichenoid flat-topped papule on the left arm revealed a mild bandlike infiltrate of lymphocytes and scattered eosinophils, eosinophilic colloid bodies and edema in the papillary dermis, and subepidermal vesicles and vacuolar alteration of the basal layer consistent with a vesicular lichenoid dermatitis (Figure 5). Direct immunofluorescence (DIF) of perilesional skin showed linear deposition of C3 and IgM along the basement membrane zone (BMZ) in addition to a shaggy pattern with cytoid bodies (Figure 6). There also was a faint linear deposit of IgA along the BMZ with cytoid bodies but negative for IgG. These results were interpreted as consistent with LP pemphigoides (LPP). Neither an enzyme-linked immunosorbent assay nor an immunoblot analysis was performed.

Because the patient was pregnant and had failed to respond to topical and intramuscular corticosteroids, she was started on intravenous methylprednisolone in the emergency department until new lesions stopped appearing. She was then discharged home on oral prednisone 50 mg (0.5 mg/kg/d), with close observation by her obstetrician. She also used clobetasol propionate ointment 0.05% for more severe lesions and triamcinolone acetonide cream 0.1% for less severe lesions until lesions resolved.

During treatment, the patient developed cellulitis on the leg that presented as pustules and erythema at a site of an eroded bulla, inframammary and axillary cutaneous candidiasis, and hyperglycemia at 19 weeks’ gestation. The cutaneous infections resolved with oral clindamycin 300 mg 3 times daily for 10 days. Topical mupirocin was used to treat the cellulitis and a mixture of zinc oxide, econazole cream, and desonide cream twice daily treated the candidiasis. Her obstetrician managed the hyperglycemia.

The bullous lesions and LP completely resolved after 2 months of treatment with oral prednisone 50 mg daily. The patient tolerated a corticosteroid taper (dose decreased by 5 mg every 2 weeks) until arriving at 10 mg, which was then decreased to 7.5 mg until delivery. A cesarean delivery was performed due to a large-for-gestational-age fetus, and an internist was consulted for the necessary precautions to increase the steroid dose during delivery due to the stress of the surgery and the risk for a hypothalamic crisis. There were no peripartum complications, and the baby was born without cutaneous lesions and remains healthy 1 year later. The patient remained disease free over 2 months postpartum, until new LP lesions developed without vesicles or bullae, which were then controlled with topical therapy. She was subsequently lost to follow-up.

Comment

Kaposi first described LPP in 1892 and used the term lichen ruber pemphigoides to describe a case of typical LP together with a widespread bullous eruption. Lichen planus pemphigoides is characterized by tense blisters that arise on lesions of LP as well as on skin unaffected by LP. In contrast, bullous LP blisters are confined to LP lesions only and occur from intense lichenoid inflammation and extensive liquefactive degeneration of basal keratinocytes. The vesicle formation in LPP is a result of autoantibodies to the bullous pemphigoid (BP) antigen BPAg2, which can be explained by the epitope spreading epiphenomenon whereby epidermotropic cytotoxic T cells damage the basal keratinocytes in LP by targeting unknown epidermal antigens, resulting in the exposure of BP180 and therefore instigating the autoimmune response.¹ The process of epitope spreading takes months to develop; the mean duration of LP before LPP is 8 weeks in children and 12 weeks in adults,² which is comparable to the current case.

Pathogenesis

Lichen planus pemphigoides usually is idiopathic; however, there have been cases reported in association with various medications including calcium channel blockers such as diltiazem, Chinese herbs,³ simvastatin,⁴ ramipril,^5,6 captopril,⁷ psoralen plus UVA phototherapy,⁸ and cinnarizine.⁹ In addition, in a case-controlled study, the use of neuroleptics or diuretics was found to be a risk factor for LPP development.¹⁰

This case is unique because it shows an association of LPP with an intrauterine pregnancy. Despite the fact that we did not perform the required studies to determine the exact cause, there probably exists an association between LPP and the pregnancy, as the patient presented with a 5-month history of severe LP prior to vesicle formation. The patient only developed the vesicular lesions during pregnancy, which were later controlled with systemic steroids and then recurred postpartum only as LP lesions, suggesting that the patient’s pregnancy may have contributed in the pathogenesis as an inducing factor. We suspect that the LP was aggravated by the pregnancy and continued to worsen, so much as to cause epitope spreading and lead to the bullous eruption at the end of the first trimester.²

Differential Diagnosis

Initially, we suspected a diagnosis of pemphigoid gestationis (PG), previously known as herpes gestationis. The classic presentation of PG starts with an intense pruritus followed by the emergence of pruritic urticarial papules and plaques in the umbilical or periumbilical areas. The lesions may become targetlike or polycyclic and may spread to other areas of the trunk, arms, and legs, often including the palms and soles.^11-15 Just as in our case, vesicles and bullous lesions appear at both the site of the urticarial plaques as well as on normal skin.16 The clinical features noted in our patient that were not typical of PG included the multiple lesions on the face and inside the nostrils. Only 20% of PG cases are associated with mucosal involvement,^11,12,15 and there are no documented reports of PG occurring in a patient with LP, according to a PubMed search of articles indexed for MEDLINE using the search terms pemphigoid gestationis, herpes gestationis, and lichen planus.

Lichen planus pemphigoides can be easily differentiated from BP. Lichen planus pemphigoides occurs in younger patients, with a mean age of 35 years, unlike BP, which commonly affects elderly men.¹⁷ Lichen planus pemphigoides also is less severe and has a better response to treatment than BP. It also affects the palms and soles, which are rarely affected in BP. There are no reports in the literature of BP developing during pregnancy, according to a PubMed search using the terms bullous pemphigoid and pregnancy. However, LPP and BP share a common antibody, the BP180 antigen, and differences exist in the epitope where the antibody binds in each condition.^18,19

Diagnosing LPP

In LPP, DIF typically shows linear deposits of IgG, IgM, IgA, fibrinogen, and C3 along the BMZ, of which IgG and C3 are most commonly seen.³ Our patient had linear deposition of C3, IgM, and IgA along the BMZ, which excluded bullous LP from the differential diagnosis. Bullous LP is not an autoimmune condition but rather is on the severe spectrum of LP where Max Joseph spaces become so large so as to lead to vesicle and bullae formation. In addition to the linear deposit at the BMZ, LPP typically reveals immunoglobulin (mainly IgM but also IgA), C3, and fibrinogen staining of colloid bodies in the papillary dermis on DIF; however, some cases of LPP only present with a linear deposition of C3 along the BMZ, which is why, similar to PG, these diagnoses by DIF are similar. Direct immunofluorescence of PG reveals linear IgG1 and IgG3 along the BMZ. IgG1 and IgG3 immunoglobulins are known to fix complement better than other immunoglobulins, thus linear C3 along the BMZ is the most consistently positive immunoreactant. Less common positive immunoreactivity with the same pattern has been seen with IgA, IgM, C1, and C4 (Table).^14,15,18 The lack of linear IgG and the presence of IgM is more suggestive of LPP.

The differential diagnosis of the subepidermal autoimmune blistering diseases associated with antibodies against BP180, including BP, LPP, and PG, often is challenging.¹⁵ However, LPP can now be distinguished by immunological studies including immunoblot analysis of the immunodominant region of NC16A of the BP180 antigen and the immunoglobulin subclass that reacts to 180-, 200-,²⁰ and 230-kDa antigens within the BMZ (Table).^15,18-20 The Table summarizes the different autoantibodies, antigens, and epitopes to distinguish subepidermal autoimmune blistering diseases.

Despite not performing these studies in our patient, we concluded that the clinical, histological, and DIF findings of this case are more consistent with LPP than with the other subepidermal blistering diseases. However, we cannot exclude the possibility of the patient having a new entity with a unique antibody from epitope spreading.

Conclusion

We present a case of lichenoid papules and plaques consistent with LP, with the development of vesicles and bullae after the first trimester of pregnancy. The clinical, pathologic, and DIF findings were highly suggestive of LPP. Although the exact pathogenic mechanism is not fully known, we suspect that pregnancy may have contributed to the origin of the disease. Further evaluation of pregnant patients with lichenoid lesions who develop blisters are needed for the elucidation of the mechanism, which may be secondary to epitope spreading that led to new autoantibody formation.

To the Editor:

Pemphigus vulgaris (PV) is an acquired autoimmune bullous disease with notable morbidity and mortality if not treated appropriately due to loss of epidermal barrier function and subsequent infection and loss of body fluids. Although the use of systemic corticosteroids and immunosuppressive agents has improved the prognosis, these drugs also may have severe adverse effects, especially in elderly patients. Hence, alternative and safer therapies with anti-inflammatory and immunomodulatory agents such as tetracyclines and nicotinamide have been used with variable results. We report a case of PV that was successfully treated with doxycycline.

An 81-year-old man presented with well-demarcated erosions with overlying yellow crust as well as vesicles and pustules on the scalp (Figure 1A), forehead, bilateral cheeks, and upper back (Figure 1B) of 6 months’ duration. He used topical fluorouracil in the month prior to presentation for suspected actinic keratosis but had stopped its use after 2 weeks. At the first visit, a diagnosis of a reaction to topical fluorouracil with secondary bacterial infection was made and he was prescribed doxycycline hyclate 100 mg twice daily. The patient returned 4 weeks later for follow-up and reported initial notable improvement with subsequent worsening of lesions after he ran out of doxycycline. On physical examination the lesions had considerably improved from the last visit, but he still had a few erosions on the scalp and a few in the oral mucosa. A 1-cm shallow erosion with minimal surrounding erythema on the forehead was present, along with fewer scattered, edematous, erythematous plaques on the back and chest. Pemphigus vulgaris was suspected and 2 shave biopsies from the lesions on the back and cheek were obtained for confirmation. Histopathologic examination revealed epidermal hyperplasia and suprabasal acantholysis as well as moderate perivascular and perifollicular lymphocytic infiltrate with several eosinophils and plasma cells, characteristic of PV (Figure 2). Direct immunofluorescence showed moderate intercellular deposition of IgG within the basal layer and to a lesser extent within suprabasal layers as well as moderate intercellular deposition of C3 within the basal layer, characteristic of PV. IgA and IgM were not present. Indirect immunofluorescence using monkey esophagus revealed no antibodies against the intercellular space of the basement membrane zone. Due to the dramatic response, he continued on doxycycline 100 mg twice daily and remained in complete remission. Ten months after initiating treatment he discontinued doxycycline for 2 days and developed a 1-cm lesion on the left cheek. He resumed treatment with clearing of lesions and was slowly tapered to 50 mg of doxycycline once daily, remaining in complete remission (Figure 3). Doxycycline was discontinued 16 months after initiation; he has remained clear at 13 weeks.

The treatment of PV is challenging given the multiple side effects of steroids, especially in elderly patients. Tetracyclines have an advantageous side-effect profile and they have been shown to be efficacious in treating PV when combined with nicotinamide or when used as adjuvant therapy to steroids.^1-3 Our case shows a patient who was treated exclusively with doxycycline and achieved complete remission.

Tetracyclines have multiple biological activities in addition to their antimicrobial function that may provide a therapeutic benefit in PV. They possess immunomodulatory and anti-inflammatory effects by inhibiting leukocyte chemotaxis and activation^4-8 and inhibiting cytokine release. They inhibit matrix metalloproteinases, which are the major enzymes responsible for breakdown of the extracellular matrix,⁹ and they indirectly inhibit neutrophil elastase by protecting α₁-protease inhibitor from matrix metalloproteinase degradation.¹⁰ Additionally, tetracyclines increase the cohesion of the dermoepidermal junction¹¹; whether they increase the adhesion between epidermal cells is unknown. It has been determined that CD4⁺ T cells play an essential role in the pathogenesis of PV by promoting anti-desmoglein 3 antibody production.¹² Szeto et al¹³ reported that minocycline, a member of the tetracycline family, has suppressive effects on CD4⁺ T-cell activation by hindering the activation of nuclear factor of activated T cells (NFAT), a key regulatory factor in T-cell activation. We hypothesize that doxycycline exerted what appears to be immunomodulatory properties in our patient by suppressing CD4⁺ T-cell activity.

In conclusion, tetracyclines can be an effective and promising therapy for PV given their relatively few side effects and immunomodulating properties. However, further randomized controlled trials will be important to support our conclusion.

To the Editor:

Pemphigus vulgaris (PV) is an acquired autoimmune bullous disease with notable morbidity and mortality if not treated appropriately due to loss of epidermal barrier function and subsequent infection and loss of body fluids. Although the use of systemic corticosteroids and immunosuppressive agents has improved the prognosis, these drugs also may have severe adverse effects, especially in elderly patients. Hence, alternative and safer therapies with anti-inflammatory and immunomodulatory agents such as tetracyclines and nicotinamide have been used with variable results. We report a case of PV that was successfully treated with doxycycline.

An 81-year-old man presented with well-demarcated erosions with overlying yellow crust as well as vesicles and pustules on the scalp (Figure 1A), forehead, bilateral cheeks, and upper back (Figure 1B) of 6 months’ duration. He used topical fluorouracil in the month prior to presentation for suspected actinic keratosis but had stopped its use after 2 weeks. At the first visit, a diagnosis of a reaction to topical fluorouracil with secondary bacterial infection was made and he was prescribed doxycycline hyclate 100 mg twice daily. The patient returned 4 weeks later for follow-up and reported initial notable improvement with subsequent worsening of lesions after he ran out of doxycycline. On physical examination the lesions had considerably improved from the last visit, but he still had a few erosions on the scalp and a few in the oral mucosa. A 1-cm shallow erosion with minimal surrounding erythema on the forehead was present, along with fewer scattered, edematous, erythematous plaques on the back and chest. Pemphigus vulgaris was suspected and 2 shave biopsies from the lesions on the back and cheek were obtained for confirmation. Histopathologic examination revealed epidermal hyperplasia and suprabasal acantholysis as well as moderate perivascular and perifollicular lymphocytic infiltrate with several eosinophils and plasma cells, characteristic of PV (Figure 2). Direct immunofluorescence showed moderate intercellular deposition of IgG within the basal layer and to a lesser extent within suprabasal layers as well as moderate intercellular deposition of C3 within the basal layer, characteristic of PV. IgA and IgM were not present. Indirect immunofluorescence using monkey esophagus revealed no antibodies against the intercellular space of the basement membrane zone. Due to the dramatic response, he continued on doxycycline 100 mg twice daily and remained in complete remission. Ten months after initiating treatment he discontinued doxycycline for 2 days and developed a 1-cm lesion on the left cheek. He resumed treatment with clearing of lesions and was slowly tapered to 50 mg of doxycycline once daily, remaining in complete remission (Figure 3). Doxycycline was discontinued 16 months after initiation; he has remained clear at 13 weeks.

The treatment of PV is challenging given the multiple side effects of steroids, especially in elderly patients. Tetracyclines have an advantageous side-effect profile and they have been shown to be efficacious in treating PV when combined with nicotinamide or when used as adjuvant therapy to steroids.^1-3 Our case shows a patient who was treated exclusively with doxycycline and achieved complete remission.

Tetracyclines have multiple biological activities in addition to their antimicrobial function that may provide a therapeutic benefit in PV. They possess immunomodulatory and anti-inflammatory effects by inhibiting leukocyte chemotaxis and activation^4-8 and inhibiting cytokine release. They inhibit matrix metalloproteinases, which are the major enzymes responsible for breakdown of the extracellular matrix,⁹ and they indirectly inhibit neutrophil elastase by protecting α₁-protease inhibitor from matrix metalloproteinase degradation.¹⁰ Additionally, tetracyclines increase the cohesion of the dermoepidermal junction¹¹; whether they increase the adhesion between epidermal cells is unknown. It has been determined that CD4⁺ T cells play an essential role in the pathogenesis of PV by promoting anti-desmoglein 3 antibody production.¹² Szeto et al¹³ reported that minocycline, a member of the tetracycline family, has suppressive effects on CD4⁺ T-cell activation by hindering the activation of nuclear factor of activated T cells (NFAT), a key regulatory factor in T-cell activation. We hypothesize that doxycycline exerted what appears to be immunomodulatory properties in our patient by suppressing CD4⁺ T-cell activity.

In conclusion, tetracyclines can be an effective and promising therapy for PV given their relatively few side effects and immunomodulating properties. However, further randomized controlled trials will be important to support our conclusion.

To the Editor:

Pemphigus vulgaris (PV) is an acquired autoimmune bullous disease with notable morbidity and mortality if not treated appropriately due to loss of epidermal barrier function and subsequent infection and loss of body fluids. Although the use of systemic corticosteroids and immunosuppressive agents has improved the prognosis, these drugs also may have severe adverse effects, especially in elderly patients. Hence, alternative and safer therapies with anti-inflammatory and immunomodulatory agents such as tetracyclines and nicotinamide have been used with variable results. We report a case of PV that was successfully treated with doxycycline.

An 81-year-old man presented with well-demarcated erosions with overlying yellow crust as well as vesicles and pustules on the scalp (Figure 1A), forehead, bilateral cheeks, and upper back (Figure 1B) of 6 months’ duration. He used topical fluorouracil in the month prior to presentation for suspected actinic keratosis but had stopped its use after 2 weeks. At the first visit, a diagnosis of a reaction to topical fluorouracil with secondary bacterial infection was made and he was prescribed doxycycline hyclate 100 mg twice daily. The patient returned 4 weeks later for follow-up and reported initial notable improvement with subsequent worsening of lesions after he ran out of doxycycline. On physical examination the lesions had considerably improved from the last visit, but he still had a few erosions on the scalp and a few in the oral mucosa. A 1-cm shallow erosion with minimal surrounding erythema on the forehead was present, along with fewer scattered, edematous, erythematous plaques on the back and chest. Pemphigus vulgaris was suspected and 2 shave biopsies from the lesions on the back and cheek were obtained for confirmation. Histopathologic examination revealed epidermal hyperplasia and suprabasal acantholysis as well as moderate perivascular and perifollicular lymphocytic infiltrate with several eosinophils and plasma cells, characteristic of PV (Figure 2). Direct immunofluorescence showed moderate intercellular deposition of IgG within the basal layer and to a lesser extent within suprabasal layers as well as moderate intercellular deposition of C3 within the basal layer, characteristic of PV. IgA and IgM were not present. Indirect immunofluorescence using monkey esophagus revealed no antibodies against the intercellular space of the basement membrane zone. Due to the dramatic response, he continued on doxycycline 100 mg twice daily and remained in complete remission. Ten months after initiating treatment he discontinued doxycycline for 2 days and developed a 1-cm lesion on the left cheek. He resumed treatment with clearing of lesions and was slowly tapered to 50 mg of doxycycline once daily, remaining in complete remission (Figure 3). Doxycycline was discontinued 16 months after initiation; he has remained clear at 13 weeks.

The treatment of PV is challenging given the multiple side effects of steroids, especially in elderly patients. Tetracyclines have an advantageous side-effect profile and they have been shown to be efficacious in treating PV when combined with nicotinamide or when used as adjuvant therapy to steroids.^1-3 Our case shows a patient who was treated exclusively with doxycycline and achieved complete remission.

Tetracyclines have multiple biological activities in addition to their antimicrobial function that may provide a therapeutic benefit in PV. They possess immunomodulatory and anti-inflammatory effects by inhibiting leukocyte chemotaxis and activation^4-8 and inhibiting cytokine release. They inhibit matrix metalloproteinases, which are the major enzymes responsible for breakdown of the extracellular matrix,⁹ and they indirectly inhibit neutrophil elastase by protecting α₁-protease inhibitor from matrix metalloproteinase degradation.¹⁰ Additionally, tetracyclines increase the cohesion of the dermoepidermal junction¹¹; whether they increase the adhesion between epidermal cells is unknown. It has been determined that CD4⁺ T cells play an essential role in the pathogenesis of PV by promoting anti-desmoglein 3 antibody production.¹² Szeto et al¹³ reported that minocycline, a member of the tetracycline family, has suppressive effects on CD4⁺ T-cell activation by hindering the activation of nuclear factor of activated T cells (NFAT), a key regulatory factor in T-cell activation. We hypothesize that doxycycline exerted what appears to be immunomodulatory properties in our patient by suppressing CD4⁺ T-cell activity.

In conclusion, tetracyclines can be an effective and promising therapy for PV given their relatively few side effects and immunomodulating properties. However, further randomized controlled trials will be important to support our conclusion.

The Diagnosis: Primary Cutaneous Mucinous Carcinoma

Primary cutaneous mucinous carcinoma is a rare tumor of the sweat glands that was first reported in 1952 by Lennox et al.¹ These tumors are slow growing and have a predilection for the head and neck, with the eyelid being the most commonly reported location.² In general, they present as erythematous asymptomatic nodules measuring less than 7 cm in diameter.^2-4 Primary cutaneous mucinous carcinoma tends to have a good prognosis with complete resection, but cases of metastasis and recurrence have been reported.² Although there is no standard of care, treatment typically consists of surgical management, as the tumors are nonresponsive to chemotherapy or radiation.⁴ Kamalpour et al² compared outcomes for Mohs micrographic surgery versus standard excision, the former showing a lower percentage of poor outcomes. Of note, there were fewer cases treated with Mohs surgery in this study; only more recently reported cases have been treated with Mohs surgery.

Histologically, primary cutaneous mucinous carcinoma is composed of cords, tubules, and lobules of epithelial cells floating in large pools of basophilic mucin, separated by thin fibrovascular septa.⁵ It can be difficult to distinguish a primary tumor from a mucinous carcinoma metastasis with histology alone, especially on the breasts and in the gastrointestinal tract. Immunohistochemistry can be helpful in determining the origin of the tumor. A homologue of p53, p63 expressed in basal and myoepithelial cells of the skin can aid in the confirmation of a primary tumor when present.^6,7 Negative staining for cytokeratin 20 and positive staining for cytokeratin 7 also are helpful in distinguishing a primary cutaneous mucinous carcinoma from a gastrointestinal tract metastasis.^4,8

In our patient, no other symptoms were present that raised concern for an internal malignancy. Findings that supported a primary versus metastatic tumor included the clinicopathologic findings (Figure) as well as positive p63, cytokeratin 7, and negative cytokeratin 20 staining. The initial standard excision had tumor cells within 1 mm of the specimen margin; thus, a subsequent wider reexcision was performed. Reexcision was negative for tumor cells. Close follow-up with a primary care physician was recommended, with emphasis on colon and breast cancer screening. A follow-up mammogram was negative for breast cancer.

The Diagnosis: Primary Cutaneous Mucinous Carcinoma

Primary cutaneous mucinous carcinoma is a rare tumor of the sweat glands that was first reported in 1952 by Lennox et al.¹ These tumors are slow growing and have a predilection for the head and neck, with the eyelid being the most commonly reported location.² In general, they present as erythematous asymptomatic nodules measuring less than 7 cm in diameter.^2-4 Primary cutaneous mucinous carcinoma tends to have a good prognosis with complete resection, but cases of metastasis and recurrence have been reported.² Although there is no standard of care, treatment typically consists of surgical management, as the tumors are nonresponsive to chemotherapy or radiation.⁴ Kamalpour et al² compared outcomes for Mohs micrographic surgery versus standard excision, the former showing a lower percentage of poor outcomes. Of note, there were fewer cases treated with Mohs surgery in this study; only more recently reported cases have been treated with Mohs surgery.

Histologically, primary cutaneous mucinous carcinoma is composed of cords, tubules, and lobules of epithelial cells floating in large pools of basophilic mucin, separated by thin fibrovascular septa.⁵ It can be difficult to distinguish a primary tumor from a mucinous carcinoma metastasis with histology alone, especially on the breasts and in the gastrointestinal tract. Immunohistochemistry can be helpful in determining the origin of the tumor. A homologue of p53, p63 expressed in basal and myoepithelial cells of the skin can aid in the confirmation of a primary tumor when present.^6,7 Negative staining for cytokeratin 20 and positive staining for cytokeratin 7 also are helpful in distinguishing a primary cutaneous mucinous carcinoma from a gastrointestinal tract metastasis.^4,8

In our patient, no other symptoms were present that raised concern for an internal malignancy. Findings that supported a primary versus metastatic tumor included the clinicopathologic findings (Figure) as well as positive p63, cytokeratin 7, and negative cytokeratin 20 staining. The initial standard excision had tumor cells within 1 mm of the specimen margin; thus, a subsequent wider reexcision was performed. Reexcision was negative for tumor cells. Close follow-up with a primary care physician was recommended, with emphasis on colon and breast cancer screening. A follow-up mammogram was negative for breast cancer.

The Diagnosis: Primary Cutaneous Mucinous Carcinoma

Primary cutaneous mucinous carcinoma is a rare tumor of the sweat glands that was first reported in 1952 by Lennox et al.¹ These tumors are slow growing and have a predilection for the head and neck, with the eyelid being the most commonly reported location.² In general, they present as erythematous asymptomatic nodules measuring less than 7 cm in diameter.^2-4 Primary cutaneous mucinous carcinoma tends to have a good prognosis with complete resection, but cases of metastasis and recurrence have been reported.² Although there is no standard of care, treatment typically consists of surgical management, as the tumors are nonresponsive to chemotherapy or radiation.⁴ Kamalpour et al² compared outcomes for Mohs micrographic surgery versus standard excision, the former showing a lower percentage of poor outcomes. Of note, there were fewer cases treated with Mohs surgery in this study; only more recently reported cases have been treated with Mohs surgery.

Histologically, primary cutaneous mucinous carcinoma is composed of cords, tubules, and lobules of epithelial cells floating in large pools of basophilic mucin, separated by thin fibrovascular septa.⁵ It can be difficult to distinguish a primary tumor from a mucinous carcinoma metastasis with histology alone, especially on the breasts and in the gastrointestinal tract. Immunohistochemistry can be helpful in determining the origin of the tumor. A homologue of p53, p63 expressed in basal and myoepithelial cells of the skin can aid in the confirmation of a primary tumor when present.^6,7 Negative staining for cytokeratin 20 and positive staining for cytokeratin 7 also are helpful in distinguishing a primary cutaneous mucinous carcinoma from a gastrointestinal tract metastasis.^4,8

In our patient, no other symptoms were present that raised concern for an internal malignancy. Findings that supported a primary versus metastatic tumor included the clinicopathologic findings (Figure) as well as positive p63, cytokeratin 7, and negative cytokeratin 20 staining. The initial standard excision had tumor cells within 1 mm of the specimen margin; thus, a subsequent wider reexcision was performed. Reexcision was negative for tumor cells. Close follow-up with a primary care physician was recommended, with emphasis on colon and breast cancer screening. A follow-up mammogram was negative for breast cancer.

The Diagnosis: Eccrine Angiomatous Hamartoma

Given the progression of symptoms 3 months prior to presentation, an excisional biopsy was performed (Figure 1). Hematoxylin and eosin staining showed prominent eccrine sweat glands and vessels surrounded by superficially located adipose tissue in the mid and deep dermis (Figure 2).

Eccrine angiomatous hamartoma (EAH) is an uncommon benign tumor typically located on the arms and legs or trunk. It is usually solitary, though cases with multiple lesions have been reported.^1,2 Most cases are diagnosed in childhood as either congenital or acquired lesions. However, EAHs can develop in adulthood and have been described in patients up to 70 years of age.³ The median age of diagnosis is 10 years,² indicating that EAH is primarily a pediatric tumor. There is no gender predilection.

Approximately 35% to 66% of patients report pain, pruritus, or hyperhidrosis associated with EAHs, though this incidence may be overrepresented because patients tend to present when the lesions become symptomatic.^2-5 The pain is attributed to nerve fibers infiltrating the tumor. Hypertrichosis also has been described and is thought to be due to hair follicles within the hamartoma.

Histologically, EAHs are characterized by normal-appearing eccrine glands mingled with venules and capillaries. Additional variable pathologic findings include lipomatous, pilar, lymphatic, or mucinous features.² Other vascular anomalies such as hemangiomas or arteriovenous malformations occasionally have been described in association with EAH. The vessels stain for ulex europaeus 1 and factor VIII. Eccrine glands stain for S-100 protein, carcinoembryonic antigen, epithelial membrane antigen, and cytokeratin CAM 5.2. In light of a publication proposing that EAH is a lymphatic proliferation,⁶ a D2-40 stain was performed on the specimen and was negative. 

Eccrine angiomatous hamartoma has been reported to grow mainly during childhood, puberty, or pregnancy, presumably due to hormonal influences.⁷ There are few reports of EAH enlarging in middle-aged adults, and even fewer without pain during the growth phase. It is unclear what triggered the growth in our otherwise healthy postmenopausal patient.

Eccrine angiomatous hamartoma does not have malignant potential and thus treatment is optional and based on relief of symptoms. Simple excision of the EAH usually is curative, but recurrences can occur.⁴ Botulinum toxin also has been used to treat hyperhidrosis in tumors that are too large for resection. Treatment with lasers such as the pulsed dye laser and Nd:YAG laser has not been successful.⁸ A case of spontaneous regression has been reported.¹

Liposuction was considered in our patient given the substantial adipose tissue on biopsy. The patient ultimately declined treatment. This case highlights that EAH can present in adulthood and should be considered in the differential diagnosis of an enlarging but otherwise asymptomatic vascular tumor.

The Diagnosis: Eccrine Angiomatous Hamartoma

Given the progression of symptoms 3 months prior to presentation, an excisional biopsy was performed (Figure 1). Hematoxylin and eosin staining showed prominent eccrine sweat glands and vessels surrounded by superficially located adipose tissue in the mid and deep dermis (Figure 2).

Eccrine angiomatous hamartoma (EAH) is an uncommon benign tumor typically located on the arms and legs or trunk. It is usually solitary, though cases with multiple lesions have been reported.^1,2 Most cases are diagnosed in childhood as either congenital or acquired lesions. However, EAHs can develop in adulthood and have been described in patients up to 70 years of age.³ The median age of diagnosis is 10 years,² indicating that EAH is primarily a pediatric tumor. There is no gender predilection.

Approximately 35% to 66% of patients report pain, pruritus, or hyperhidrosis associated with EAHs, though this incidence may be overrepresented because patients tend to present when the lesions become symptomatic.^2-5 The pain is attributed to nerve fibers infiltrating the tumor. Hypertrichosis also has been described and is thought to be due to hair follicles within the hamartoma.

Histologically, EAHs are characterized by normal-appearing eccrine glands mingled with venules and capillaries. Additional variable pathologic findings include lipomatous, pilar, lymphatic, or mucinous features.² Other vascular anomalies such as hemangiomas or arteriovenous malformations occasionally have been described in association with EAH. The vessels stain for ulex europaeus 1 and factor VIII. Eccrine glands stain for S-100 protein, carcinoembryonic antigen, epithelial membrane antigen, and cytokeratin CAM 5.2. In light of a publication proposing that EAH is a lymphatic proliferation,⁶ a D2-40 stain was performed on the specimen and was negative. 

Eccrine angiomatous hamartoma has been reported to grow mainly during childhood, puberty, or pregnancy, presumably due to hormonal influences.⁷ There are few reports of EAH enlarging in middle-aged adults, and even fewer without pain during the growth phase. It is unclear what triggered the growth in our otherwise healthy postmenopausal patient.

Eccrine angiomatous hamartoma does not have malignant potential and thus treatment is optional and based on relief of symptoms. Simple excision of the EAH usually is curative, but recurrences can occur.⁴ Botulinum toxin also has been used to treat hyperhidrosis in tumors that are too large for resection. Treatment with lasers such as the pulsed dye laser and Nd:YAG laser has not been successful.⁸ A case of spontaneous regression has been reported.¹

Liposuction was considered in our patient given the substantial adipose tissue on biopsy. The patient ultimately declined treatment. This case highlights that EAH can present in adulthood and should be considered in the differential diagnosis of an enlarging but otherwise asymptomatic vascular tumor.

The Diagnosis: Eccrine Angiomatous Hamartoma

Given the progression of symptoms 3 months prior to presentation, an excisional biopsy was performed (Figure 1). Hematoxylin and eosin staining showed prominent eccrine sweat glands and vessels surrounded by superficially located adipose tissue in the mid and deep dermis (Figure 2).

Eccrine angiomatous hamartoma (EAH) is an uncommon benign tumor typically located on the arms and legs or trunk. It is usually solitary, though cases with multiple lesions have been reported.^1,2 Most cases are diagnosed in childhood as either congenital or acquired lesions. However, EAHs can develop in adulthood and have been described in patients up to 70 years of age.³ The median age of diagnosis is 10 years,² indicating that EAH is primarily a pediatric tumor. There is no gender predilection.

Approximately 35% to 66% of patients report pain, pruritus, or hyperhidrosis associated with EAHs, though this incidence may be overrepresented because patients tend to present when the lesions become symptomatic.^2-5 The pain is attributed to nerve fibers infiltrating the tumor. Hypertrichosis also has been described and is thought to be due to hair follicles within the hamartoma.

Histologically, EAHs are characterized by normal-appearing eccrine glands mingled with venules and capillaries. Additional variable pathologic findings include lipomatous, pilar, lymphatic, or mucinous features.² Other vascular anomalies such as hemangiomas or arteriovenous malformations occasionally have been described in association with EAH. The vessels stain for ulex europaeus 1 and factor VIII. Eccrine glands stain for S-100 protein, carcinoembryonic antigen, epithelial membrane antigen, and cytokeratin CAM 5.2. In light of a publication proposing that EAH is a lymphatic proliferation,⁶ a D2-40 stain was performed on the specimen and was negative. 

Eccrine angiomatous hamartoma has been reported to grow mainly during childhood, puberty, or pregnancy, presumably due to hormonal influences.⁷ There are few reports of EAH enlarging in middle-aged adults, and even fewer without pain during the growth phase. It is unclear what triggered the growth in our otherwise healthy postmenopausal patient.

Eccrine angiomatous hamartoma does not have malignant potential and thus treatment is optional and based on relief of symptoms. Simple excision of the EAH usually is curative, but recurrences can occur.⁴ Botulinum toxin also has been used to treat hyperhidrosis in tumors that are too large for resection. Treatment with lasers such as the pulsed dye laser and Nd:YAG laser has not been successful.⁸ A case of spontaneous regression has been reported.¹

Liposuction was considered in our patient given the substantial adipose tissue on biopsy. The patient ultimately declined treatment. This case highlights that EAH can present in adulthood and should be considered in the differential diagnosis of an enlarging but otherwise asymptomatic vascular tumor.

Nuchal-Type Fibroma

Nuchal-type fibroma (NTF) is a rare benign proliferation of the dermis and subcutis associated with diabetes mellitus and Gardner syndrome.^1,2 Forty-four percent of patients with NTF have diabetes mellitus.² The posterior aspect of the neck is the most frequently affected site, but lesions also may present on the upper back, lumbosacral area, buttocks, and face. Physical examination generally reveals an indurated, asymptomatic, ill-defined, 3-cm or smaller nodule that is hard and white, unencapsulated, and poorly circumscribed.

Histopathologic examination of NTF typically reveals a nodular paucicellular proliferation of thick collagen bundles with inconspicuous fibroblasts, radiation of collagenous septa into the subcutaneous fat, and entrapment of mature adipose tissue and small nerves (quiz image A). Collagen bundles are thickened with entrapment of adipose tissue without increased cellularity (quiz image B). S-100 staining can show the entrapped nerves.

Similar to NTF, sclerotic fibroma is a firm dermal nodule with histologic examination usually demonstrating a paucicellular collagenous tumor. In sclerotic fibromas, the collagen pattern resembles Vincent van Gogh’s painting “The Starry Night” and may be a marker for Cowden disease (Figure 1).³ Solitary fibrous tumors are distinguished by more hypercellular areas, patternless pattern, and staghorn-shaped blood vessels (Figure 2).⁴ Spindle cell lipoma classically demonstrates a mixture of mature adipocytes and bland spindle cells in a mucinous or fibrous background with thick collagen bundles with no storiform pattern (Figure 3). Some variants of spindle cell lipoma have minimal or no fat.⁵ All of these conditions have positive immunohistochemical staining for CD34.

However, dermatofibroma is CD34‒. Dermatofibroma is characterized by an interstitial spindle cell proliferation with a loose storiform pattern, collagen trapping at the outer edges of the tumor, overlying platelike acanthosis, and sometimes follicular induction (Figure 4).

Nuchal-type fibroma also can resemble scleredema. Both lesions can show increased and thickened collagen bundles without notable fibroblast proliferation; the difference is the occurrence of mucin in scleredema. However, incases of late-stage scleredema, mucin is not always demonstrated. Therefore, one can conclude that histologically NTF is closely associated with late-stage scleredema.⁶

Nuchal-Type Fibroma

Nuchal-type fibroma (NTF) is a rare benign proliferation of the dermis and subcutis associated with diabetes mellitus and Gardner syndrome.^1,2 Forty-four percent of patients with NTF have diabetes mellitus.² The posterior aspect of the neck is the most frequently affected site, but lesions also may present on the upper back, lumbosacral area, buttocks, and face. Physical examination generally reveals an indurated, asymptomatic, ill-defined, 3-cm or smaller nodule that is hard and white, unencapsulated, and poorly circumscribed.

Histopathologic examination of NTF typically reveals a nodular paucicellular proliferation of thick collagen bundles with inconspicuous fibroblasts, radiation of collagenous septa into the subcutaneous fat, and entrapment of mature adipose tissue and small nerves (quiz image A). Collagen bundles are thickened with entrapment of adipose tissue without increased cellularity (quiz image B). S-100 staining can show the entrapped nerves.

Similar to NTF, sclerotic fibroma is a firm dermal nodule with histologic examination usually demonstrating a paucicellular collagenous tumor. In sclerotic fibromas, the collagen pattern resembles Vincent van Gogh’s painting “The Starry Night” and may be a marker for Cowden disease (Figure 1).³ Solitary fibrous tumors are distinguished by more hypercellular areas, patternless pattern, and staghorn-shaped blood vessels (Figure 2).⁴ Spindle cell lipoma classically demonstrates a mixture of mature adipocytes and bland spindle cells in a mucinous or fibrous background with thick collagen bundles with no storiform pattern (Figure 3). Some variants of spindle cell lipoma have minimal or no fat.⁵ All of these conditions have positive immunohistochemical staining for CD34.

However, dermatofibroma is CD34‒. Dermatofibroma is characterized by an interstitial spindle cell proliferation with a loose storiform pattern, collagen trapping at the outer edges of the tumor, overlying platelike acanthosis, and sometimes follicular induction (Figure 4).

Nuchal-type fibroma also can resemble scleredema. Both lesions can show increased and thickened collagen bundles without notable fibroblast proliferation; the difference is the occurrence of mucin in scleredema. However, incases of late-stage scleredema, mucin is not always demonstrated. Therefore, one can conclude that histologically NTF is closely associated with late-stage scleredema.⁶

Nuchal-Type Fibroma

Nuchal-type fibroma (NTF) is a rare benign proliferation of the dermis and subcutis associated with diabetes mellitus and Gardner syndrome.^1,2 Forty-four percent of patients with NTF have diabetes mellitus.² The posterior aspect of the neck is the most frequently affected site, but lesions also may present on the upper back, lumbosacral area, buttocks, and face. Physical examination generally reveals an indurated, asymptomatic, ill-defined, 3-cm or smaller nodule that is hard and white, unencapsulated, and poorly circumscribed.

Histopathologic examination of NTF typically reveals a nodular paucicellular proliferation of thick collagen bundles with inconspicuous fibroblasts, radiation of collagenous septa into the subcutaneous fat, and entrapment of mature adipose tissue and small nerves (quiz image A). Collagen bundles are thickened with entrapment of adipose tissue without increased cellularity (quiz image B). S-100 staining can show the entrapped nerves.

Similar to NTF, sclerotic fibroma is a firm dermal nodule with histologic examination usually demonstrating a paucicellular collagenous tumor. In sclerotic fibromas, the collagen pattern resembles Vincent van Gogh’s painting “The Starry Night” and may be a marker for Cowden disease (Figure 1).³ Solitary fibrous tumors are distinguished by more hypercellular areas, patternless pattern, and staghorn-shaped blood vessels (Figure 2).⁴ Spindle cell lipoma classically demonstrates a mixture of mature adipocytes and bland spindle cells in a mucinous or fibrous background with thick collagen bundles with no storiform pattern (Figure 3). Some variants of spindle cell lipoma have minimal or no fat.⁵ All of these conditions have positive immunohistochemical staining for CD34.

However, dermatofibroma is CD34‒. Dermatofibroma is characterized by an interstitial spindle cell proliferation with a loose storiform pattern, collagen trapping at the outer edges of the tumor, overlying platelike acanthosis, and sometimes follicular induction (Figure 4).

Nuchal-type fibroma also can resemble scleredema. Both lesions can show increased and thickened collagen bundles without notable fibroblast proliferation; the difference is the occurrence of mucin in scleredema. However, incases of late-stage scleredema, mucin is not always demonstrated. Therefore, one can conclude that histologically NTF is closely associated with late-stage scleredema.⁶

The Diagnosis: Fibroepithelioma of Pinkus

Fibroepithelioma of Pinkus (FeP) was first described in 1953¹ and was thought to be premalignant as evidenced by the proposed name premalignant fibroepithelial tumor of the skin. This neoplasm now is largely believed to represent a rare form of basal cell carcinoma (BCC). Typical presentation is a smooth, flesh-colored or pink plaque or nodule.² Fibroepithelioma of Pinkus has a predilection for the lumbosacral back, though the groin also has been reported as a common site of incidence.^1,3 Similar to other BCCs, it is seen in older individuals, typically those older than 50 years.^3,4

Clinical diagnosis of FeP can be difficult. The differential diagnosis of FeP can include acrochordon, amelanotic melanoma, compound nevus, hemangioma, neurofibroma, nevus sebaceous, pyogenic granuloma, and seborrheic keratosis.⁵ Dermoscopic evaluation can aid in the diagnosis. A vascular network composed of fine arborizing vessels with or without dotted vessels and white streaks are characteristic findings of FeP. Patients with pigment also demonstrate structureless gray-brown areas and gray-blue dots.⁶

Biopsy with subsequent histopathologic evaluation confirms the diagnosis of FeP. The characteristic microscopic findings of thin eosinophilic epithelial strands with eccrine ducts anastomosing in an abundant fibromyxoid stroma with collections of basophilic cells located at the ends of the epithelial strands were demonstrated in our patient’s histopathologic specimen (Figure). The histologic appearance is similar to syringofibroadenoma of Mascaro. Recognition of basaloid nests, which often demonstrate retraction, and mitotic activity can differentiate FeP from syringofibroadenoma of Mascaro.⁷

Treatment of FeP is largely the same as other BCCs including destruction by electrodesiccation and curettage or complete removal by surgical excision. Several studies have demonstrated effective treatment of nonaggressive BCCs with curettage alone and subjectively reported improved cosmesis compared to electrodesiccation and curettage.^8-10 Although methyl aminolevulinate photodynamic therapy has demonstrated some therapeutic efficacy for superficial and nodular BCCs,¹¹ a case report utilizing the same modality for FeP did not provide adequate response.¹² However, adequate data are not available to assess potential use of this less invasive therapy.

The Diagnosis: Fibroepithelioma of Pinkus

Fibroepithelioma of Pinkus (FeP) was first described in 1953¹ and was thought to be premalignant as evidenced by the proposed name premalignant fibroepithelial tumor of the skin. This neoplasm now is largely believed to represent a rare form of basal cell carcinoma (BCC). Typical presentation is a smooth, flesh-colored or pink plaque or nodule.² Fibroepithelioma of Pinkus has a predilection for the lumbosacral back, though the groin also has been reported as a common site of incidence.^1,3 Similar to other BCCs, it is seen in older individuals, typically those older than 50 years.^3,4

Clinical diagnosis of FeP can be difficult. The differential diagnosis of FeP can include acrochordon, amelanotic melanoma, compound nevus, hemangioma, neurofibroma, nevus sebaceous, pyogenic granuloma, and seborrheic keratosis.⁵ Dermoscopic evaluation can aid in the diagnosis. A vascular network composed of fine arborizing vessels with or without dotted vessels and white streaks are characteristic findings of FeP. Patients with pigment also demonstrate structureless gray-brown areas and gray-blue dots.⁶

Biopsy with subsequent histopathologic evaluation confirms the diagnosis of FeP. The characteristic microscopic findings of thin eosinophilic epithelial strands with eccrine ducts anastomosing in an abundant fibromyxoid stroma with collections of basophilic cells located at the ends of the epithelial strands were demonstrated in our patient’s histopathologic specimen (Figure). The histologic appearance is similar to syringofibroadenoma of Mascaro. Recognition of basaloid nests, which often demonstrate retraction, and mitotic activity can differentiate FeP from syringofibroadenoma of Mascaro.⁷

Treatment of FeP is largely the same as other BCCs including destruction by electrodesiccation and curettage or complete removal by surgical excision. Several studies have demonstrated effective treatment of nonaggressive BCCs with curettage alone and subjectively reported improved cosmesis compared to electrodesiccation and curettage.^8-10 Although methyl aminolevulinate photodynamic therapy has demonstrated some therapeutic efficacy for superficial and nodular BCCs,¹¹ a case report utilizing the same modality for FeP did not provide adequate response.¹² However, adequate data are not available to assess potential use of this less invasive therapy.

The Diagnosis: Fibroepithelioma of Pinkus

Fibroepithelioma of Pinkus (FeP) was first described in 1953¹ and was thought to be premalignant as evidenced by the proposed name premalignant fibroepithelial tumor of the skin. This neoplasm now is largely believed to represent a rare form of basal cell carcinoma (BCC). Typical presentation is a smooth, flesh-colored or pink plaque or nodule.² Fibroepithelioma of Pinkus has a predilection for the lumbosacral back, though the groin also has been reported as a common site of incidence.^1,3 Similar to other BCCs, it is seen in older individuals, typically those older than 50 years.^3,4

Clinical diagnosis of FeP can be difficult. The differential diagnosis of FeP can include acrochordon, amelanotic melanoma, compound nevus, hemangioma, neurofibroma, nevus sebaceous, pyogenic granuloma, and seborrheic keratosis.⁵ Dermoscopic evaluation can aid in the diagnosis. A vascular network composed of fine arborizing vessels with or without dotted vessels and white streaks are characteristic findings of FeP. Patients with pigment also demonstrate structureless gray-brown areas and gray-blue dots.⁶

Biopsy with subsequent histopathologic evaluation confirms the diagnosis of FeP. The characteristic microscopic findings of thin eosinophilic epithelial strands with eccrine ducts anastomosing in an abundant fibromyxoid stroma with collections of basophilic cells located at the ends of the epithelial strands were demonstrated in our patient’s histopathologic specimen (Figure). The histologic appearance is similar to syringofibroadenoma of Mascaro. Recognition of basaloid nests, which often demonstrate retraction, and mitotic activity can differentiate FeP from syringofibroadenoma of Mascaro.⁷

Treatment of FeP is largely the same as other BCCs including destruction by electrodesiccation and curettage or complete removal by surgical excision. Several studies have demonstrated effective treatment of nonaggressive BCCs with curettage alone and subjectively reported improved cosmesis compared to electrodesiccation and curettage.^8-10 Although methyl aminolevulinate photodynamic therapy has demonstrated some therapeutic efficacy for superficial and nodular BCCs,¹¹ a case report utilizing the same modality for FeP did not provide adequate response.¹² However, adequate data are not available to assess potential use of this less invasive therapy.

Lymphomatoid papulosis (LyP) is a clinicopathologic variant of CD30⁺ primary cutaneous T-cell lymphoproliferative disorder characterized by a chronic, recurrent, self-healing eruption of papules and small nodules. From a clinical point of view, LyP is not considered a malignant disorder despite demonstration of clonality in most cases.¹ From a histopathologic point of view, there are 5 types of LyP: (1) type A, the most common type, which is characterized by a wedge-shaped infiltrate composed of clustered large atypical cells admixed with neutrophils, eosinophils, histiocytes, and small lymphocytes; (2) type B, a rare variant characterized by a bandlike infiltrate of small- to medium-sized pleomorphic and hyperchromatic lymphocytes involving the superficial dermis with epidermotropism; (3) type C, which consists of a nodular infiltrate of large atypical cells with a cohesive arrangement closely similar to anaplastic large-cell lymphoma; (4) type D, a variant with histopathologic features that resemble primary cutaneous aggressive epidermotropic CD8⁺ cytotoxic T-cell lymphoma, but neoplastic cells express CD30 and a T-cell cytotoxic phenotype (βF1⁺, CD3+, CD4^‒, CD8⁺), and follow-up usually does not reveal development of systemic involvement or signs of other cutaneous lymphomas²; and (5) type E, which is characterized by oligolesional papules that rapidly ulcerate and evolve into large, necrotic, escharlike lesions with a diameter of 1 to 4 cm and an angiocentric and angiodestructive infiltrate of small- to medium-sized atypical lymphocytes expressing CD30 and frequently CD8.³

The clinical appearance of LyP usually is polymorphic, with lesions in different stages of evolution scattered all over the skin; however, the lesions are occasionally localized only to one area of the skin, the so-called regional or agminated LyP.^4-14 We report a case of regional LyP that exclusively involved the skin of the left breast, which had previously received radiotherapy for treatment of breast carcinoma. Lymphomatoid papulosis with cutaneous lesions involving only an area of irradiated skin is rare.

Case Report

A 59-year-old woman presented with new-onset cutaneous lesions on the left breast. The patient had a history of invasive ductal carcinoma of the left breast, which had been treated 5 years prior with a partial mastectomy and radiotherapy (10 Gy per week for 5 consecutive weeks [50 Gy total]). Physical examination revealed a large nodular lesion with a necrotic surface on the upper half of the left breast as well as 3 small papular lesions with eroded surfaces on the lower half of the breast (Figure 1). A clinical diagnosis of cutaneous metastases from breast carcinoma was suspected.

Biopsies from one small papule and the large nodular lesion showed similar findings consisting of a necrotic epidermis covered by crusts and a wedge-shaped infiltrate involving the superficial dermis (Figure 2A). The infiltrate was mostly composed of large atypical mononuclear cells with oval to kidney-shaped nuclei, prominent nucleoli, and ample basophilic cytoplasm. Many mitotic figures were seen within the infiltrate (Figure 2B). The infiltrate of atypical cells was admixed with small lymphocytes, histiocytes, and some eosinophils. Immunohistochemically, the large atypical cells expressed CD2, CD3, CD4, CD45, CD30, and epithelial membrane antigen (Figures 2C and 2D). A few atypical cells also expressed CD8 and T-cell intracellular antigen 1. Approximately 60% of the nuclei of the atypical cells showed MIB-1 positivity, while CD20, CD56, AE1/AE3, S-100 protein, CD34, and CD31 were negative. The anaplastic lymphoma kinase was not expressed in atypical cells. Monoclonal rearrangement of the γ T-cell receptor was demonstrated on polymerase chain reaction. Physical examination showed no lymphadenopathy in any lymph node chains. Computed tomography of the chest and abdomen failed to demonstrate systemic involvement. On the basis of these clinical, histologic, immunohistochemical, and molecular results, a diagnosis of type A regional LyP was established.

The patient was treated with 2 daily applications of clobetasol propionate cream 0.5 mg/g and 10 mg of oral methotrexate per week for 4 weeks. After 4 weeks of treatment, the lesions on the left breast had resolved leaving slightly atrophic scars. Six months later, an episode of recurrent papular lesions occurred in the same area and responded to the same treatment, but no systemic involvement had been found.

Comment

Regional LyP is a rare variant, with only a few reported cases in the literature.^4-18 Scarisbrick et al⁴ originally reported 4 patients with LyP limited to specific regions. Interestingly, one of the patients had mycosis fungoides and the LyP lesions were confined to the same region where the mycosis fungoides lesions were observed.⁴ In a review of LyP in patients from the Netherlands (n=118), lesions limited to a specific region of the body were observed in 13% of cases.⁵ Cases of LyP limited to acral skin also have been reported.^6-8 Heald et al⁹ described 7 patients who had continuing eruptions of papulonodules with histopathologic features of LyP within well-circumscribed areas of the skin. The investigators interpreted this localized variant of LyP as an equivalent of the limited plaque stage of mycosis fungoides. Interestingly, one of the patients with LyP eventually developed plaques of mycosis fungoides in other areas of the skin not involved by LyP.⁹ Sharma et al¹⁰ described an additional example of regional LyP, and Nakahigashi et al¹¹ described a patient with tumor-stage mycosis fungoides who subsequently developed regional LyP involving the right side of the chest. Kim et al¹² described a patient with recurrent episodes of regional LyP exclusively involving the periorbital skin, and Torrelo et al¹³ reported a 12-year-old boy with persistent lesions of LyP involving the skin of the right side of the abdomen. Coelho et al¹⁴ reported a 13-year-old adolescent girl who presented with recurrent papules of LyP exclusively involving the left upper arm. Buder et al¹⁵ reported a case of LyP limited to Becker melanosis. Shang et al¹⁶ described an additional caseof regional LyP that was successfully controlled by interferon alfa-2b and nitrogen mustard solution. Haus et al¹⁷ reported type A LyP confined to the cutaneous area within a red tattoo. Finally, Wang et al¹⁸ reported a case of regional LyP in association with pseudoepitheliomatous hyperplasia

Several dermatoses may appear as specific isomorphic responses to various external stimuli, and it is possible that radiotherapy induces some damage that favors the location of the lesions because the irradiated skin behaves as a locus minoris resistentiae. Pemphigus vulgaris,^19,20 Sweet syndrome,²¹ cutaneous angiosarcoma,^22-32 and cutaneous metastases from malignant melanoma also have been reported to be confined to irradiated skin.³³ However, in our PubMed search of articles indexed for MEDLINE using the terms lymphomatoid papules and regional, none of the previously reported cases of regional LyP had a history of radiotherapy, and in no instance did the lesions develop on a previously irradiated area of the skin.^4-18 The localization of the lesions in our patient could have been the result of the so-called radiation recall phenomenon. Recall dermatitis is defined as a skin reaction in a previously irradiated field, usually subsequent to the administration of cytotoxic drugs or antibiotics.³⁴ It may appear days to years after exposure to ionizing radiation and has mostly been associated with chemotherapy drugs, but recall dermatitis is neither exclusive of chemotherapy medications nor strictly radiotherapy induced. The concept of recall dermatitis has been expanded beyond radiation recall dermatitis to include dermatitis induced by other stimuli, including other drugs, contact irritants, and UV radiation, as well as residual herpes zoster. Nevertheless, in recall dermatitis the triggering drug or agent recalls a prior dermatitis in the involved area, such as sunburn or radiodermatitis. In our patient, there was no history of LyP prior to irradiation of the left breast; therefore, the most plausible interpretation of the peculiar localization of the lesions in our patient seems to be that the eruption resulted as expression of a locus minoris resistentiae.

Distinction between primary cutaneous anaplastic large-cell lymphoma and LyP may be difficult because the histopathologic and immunophenotypic features may overlap. In our case, the presence of several papular lesions and one large nodule are more consistent, from a clinical point of view, with a diagnosis of LyP rather than primary cutaneous anaplastic large-cell lymphoma, which usually presents with a solitary and often large, ulcerated, reddish brown tumor. In our patient, the absence of lymphadenopathy, negative results of the computed tomography of the chest and abdomen, and lack of expression for anaplastic lymphoma kinase in atypical cells of the infiltrate militate against a diagnosis of secondary cutaneous involvement from nodal disease.

The histopathologic differential diagnosis of the current case also included cutaneous CD30⁺ epithelioid angiosarcoma of the breast. Weed and Folpe³⁵ reported the case of an 85-year-old woman who developed a CD30⁺ epithelioid angiosarcoma on the breast after undergoing breast-conserving surgery and adjuvant radiotherapy for treatment of an infiltrating ductal carcinoma of the breast. Histopathology showed a diffuse replacement of the dermis by a highly malignant-appearing epithelioid neoplasm growing in a solid sheet. Neoplastic cells expressed strong CD30 immunoreactivity with absence of immunoexpression for cytokeratins, S-100 protein, and CD45. Additional immunostaining demonstrated that neoplastic cells also expressed strong immunoreactivity for CD31 and the friend leukemia virus integration 1 gene, FLI-1, and focal positivity for von Willebrand factor, supporting a diagnosis of epithelioid angiosarcoma.³⁵ In our patient, CD34 and CD31 were negative, which ruled out the endothelial nature of neoplastic cells.

Conclusion

In summary, we report an example of regional LyP limited to the left breast of a woman with a history of partial mastectomy and adjuvant radiotherapy for treatment of invasive ductal breast carcinoma. It is a rare case of regional LyP exclusively involving an irradiated area of the skin.

Lymphomatoid papulosis (LyP) is a clinicopathologic variant of CD30⁺ primary cutaneous T-cell lymphoproliferative disorder characterized by a chronic, recurrent, self-healing eruption of papules and small nodules. From a clinical point of view, LyP is not considered a malignant disorder despite demonstration of clonality in most cases.¹ From a histopathologic point of view, there are 5 types of LyP: (1) type A, the most common type, which is characterized by a wedge-shaped infiltrate composed of clustered large atypical cells admixed with neutrophils, eosinophils, histiocytes, and small lymphocytes; (2) type B, a rare variant characterized by a bandlike infiltrate of small- to medium-sized pleomorphic and hyperchromatic lymphocytes involving the superficial dermis with epidermotropism; (3) type C, which consists of a nodular infiltrate of large atypical cells with a cohesive arrangement closely similar to anaplastic large-cell lymphoma; (4) type D, a variant with histopathologic features that resemble primary cutaneous aggressive epidermotropic CD8⁺ cytotoxic T-cell lymphoma, but neoplastic cells express CD30 and a T-cell cytotoxic phenotype (βF1⁺, CD3+, CD4^‒, CD8⁺), and follow-up usually does not reveal development of systemic involvement or signs of other cutaneous lymphomas²; and (5) type E, which is characterized by oligolesional papules that rapidly ulcerate and evolve into large, necrotic, escharlike lesions with a diameter of 1 to 4 cm and an angiocentric and angiodestructive infiltrate of small- to medium-sized atypical lymphocytes expressing CD30 and frequently CD8.³

The clinical appearance of LyP usually is polymorphic, with lesions in different stages of evolution scattered all over the skin; however, the lesions are occasionally localized only to one area of the skin, the so-called regional or agminated LyP.^4-14 We report a case of regional LyP that exclusively involved the skin of the left breast, which had previously received radiotherapy for treatment of breast carcinoma. Lymphomatoid papulosis with cutaneous lesions involving only an area of irradiated skin is rare.

Case Report

A 59-year-old woman presented with new-onset cutaneous lesions on the left breast. The patient had a history of invasive ductal carcinoma of the left breast, which had been treated 5 years prior with a partial mastectomy and radiotherapy (10 Gy per week for 5 consecutive weeks [50 Gy total]). Physical examination revealed a large nodular lesion with a necrotic surface on the upper half of the left breast as well as 3 small papular lesions with eroded surfaces on the lower half of the breast (Figure 1). A clinical diagnosis of cutaneous metastases from breast carcinoma was suspected.

Biopsies from one small papule and the large nodular lesion showed similar findings consisting of a necrotic epidermis covered by crusts and a wedge-shaped infiltrate involving the superficial dermis (Figure 2A). The infiltrate was mostly composed of large atypical mononuclear cells with oval to kidney-shaped nuclei, prominent nucleoli, and ample basophilic cytoplasm. Many mitotic figures were seen within the infiltrate (Figure 2B). The infiltrate of atypical cells was admixed with small lymphocytes, histiocytes, and some eosinophils. Immunohistochemically, the large atypical cells expressed CD2, CD3, CD4, CD45, CD30, and epithelial membrane antigen (Figures 2C and 2D). A few atypical cells also expressed CD8 and T-cell intracellular antigen 1. Approximately 60% of the nuclei of the atypical cells showed MIB-1 positivity, while CD20, CD56, AE1/AE3, S-100 protein, CD34, and CD31 were negative. The anaplastic lymphoma kinase was not expressed in atypical cells. Monoclonal rearrangement of the γ T-cell receptor was demonstrated on polymerase chain reaction. Physical examination showed no lymphadenopathy in any lymph node chains. Computed tomography of the chest and abdomen failed to demonstrate systemic involvement. On the basis of these clinical, histologic, immunohistochemical, and molecular results, a diagnosis of type A regional LyP was established.

The patient was treated with 2 daily applications of clobetasol propionate cream 0.5 mg/g and 10 mg of oral methotrexate per week for 4 weeks. After 4 weeks of treatment, the lesions on the left breast had resolved leaving slightly atrophic scars. Six months later, an episode of recurrent papular lesions occurred in the same area and responded to the same treatment, but no systemic involvement had been found.

Comment

Regional LyP is a rare variant, with only a few reported cases in the literature.^4-18 Scarisbrick et al⁴ originally reported 4 patients with LyP limited to specific regions. Interestingly, one of the patients had mycosis fungoides and the LyP lesions were confined to the same region where the mycosis fungoides lesions were observed.⁴ In a review of LyP in patients from the Netherlands (n=118), lesions limited to a specific region of the body were observed in 13% of cases.⁵ Cases of LyP limited to acral skin also have been reported.^6-8 Heald et al⁹ described 7 patients who had continuing eruptions of papulonodules with histopathologic features of LyP within well-circumscribed areas of the skin. The investigators interpreted this localized variant of LyP as an equivalent of the limited plaque stage of mycosis fungoides. Interestingly, one of the patients with LyP eventually developed plaques of mycosis fungoides in other areas of the skin not involved by LyP.⁹ Sharma et al¹⁰ described an additional example of regional LyP, and Nakahigashi et al¹¹ described a patient with tumor-stage mycosis fungoides who subsequently developed regional LyP involving the right side of the chest. Kim et al¹² described a patient with recurrent episodes of regional LyP exclusively involving the periorbital skin, and Torrelo et al¹³ reported a 12-year-old boy with persistent lesions of LyP involving the skin of the right side of the abdomen. Coelho et al¹⁴ reported a 13-year-old adolescent girl who presented with recurrent papules of LyP exclusively involving the left upper arm. Buder et al¹⁵ reported a case of LyP limited to Becker melanosis. Shang et al¹⁶ described an additional caseof regional LyP that was successfully controlled by interferon alfa-2b and nitrogen mustard solution. Haus et al¹⁷ reported type A LyP confined to the cutaneous area within a red tattoo. Finally, Wang et al¹⁸ reported a case of regional LyP in association with pseudoepitheliomatous hyperplasia

Several dermatoses may appear as specific isomorphic responses to various external stimuli, and it is possible that radiotherapy induces some damage that favors the location of the lesions because the irradiated skin behaves as a locus minoris resistentiae. Pemphigus vulgaris,^19,20 Sweet syndrome,²¹ cutaneous angiosarcoma,^22-32 and cutaneous metastases from malignant melanoma also have been reported to be confined to irradiated skin.³³ However, in our PubMed search of articles indexed for MEDLINE using the terms lymphomatoid papules and regional, none of the previously reported cases of regional LyP had a history of radiotherapy, and in no instance did the lesions develop on a previously irradiated area of the skin.^4-18 The localization of the lesions in our patient could have been the result of the so-called radiation recall phenomenon. Recall dermatitis is defined as a skin reaction in a previously irradiated field, usually subsequent to the administration of cytotoxic drugs or antibiotics.³⁴ It may appear days to years after exposure to ionizing radiation and has mostly been associated with chemotherapy drugs, but recall dermatitis is neither exclusive of chemotherapy medications nor strictly radiotherapy induced. The concept of recall dermatitis has been expanded beyond radiation recall dermatitis to include dermatitis induced by other stimuli, including other drugs, contact irritants, and UV radiation, as well as residual herpes zoster. Nevertheless, in recall dermatitis the triggering drug or agent recalls a prior dermatitis in the involved area, such as sunburn or radiodermatitis. In our patient, there was no history of LyP prior to irradiation of the left breast; therefore, the most plausible interpretation of the peculiar localization of the lesions in our patient seems to be that the eruption resulted as expression of a locus minoris resistentiae.

Distinction between primary cutaneous anaplastic large-cell lymphoma and LyP may be difficult because the histopathologic and immunophenotypic features may overlap. In our case, the presence of several papular lesions and one large nodule are more consistent, from a clinical point of view, with a diagnosis of LyP rather than primary cutaneous anaplastic large-cell lymphoma, which usually presents with a solitary and often large, ulcerated, reddish brown tumor. In our patient, the absence of lymphadenopathy, negative results of the computed tomography of the chest and abdomen, and lack of expression for anaplastic lymphoma kinase in atypical cells of the infiltrate militate against a diagnosis of secondary cutaneous involvement from nodal disease.

The histopathologic differential diagnosis of the current case also included cutaneous CD30⁺ epithelioid angiosarcoma of the breast. Weed and Folpe³⁵ reported the case of an 85-year-old woman who developed a CD30⁺ epithelioid angiosarcoma on the breast after undergoing breast-conserving surgery and adjuvant radiotherapy for treatment of an infiltrating ductal carcinoma of the breast. Histopathology showed a diffuse replacement of the dermis by a highly malignant-appearing epithelioid neoplasm growing in a solid sheet. Neoplastic cells expressed strong CD30 immunoreactivity with absence of immunoexpression for cytokeratins, S-100 protein, and CD45. Additional immunostaining demonstrated that neoplastic cells also expressed strong immunoreactivity for CD31 and the friend leukemia virus integration 1 gene, FLI-1, and focal positivity for von Willebrand factor, supporting a diagnosis of epithelioid angiosarcoma.³⁵ In our patient, CD34 and CD31 were negative, which ruled out the endothelial nature of neoplastic cells.

Conclusion

In summary, we report an example of regional LyP limited to the left breast of a woman with a history of partial mastectomy and adjuvant radiotherapy for treatment of invasive ductal breast carcinoma. It is a rare case of regional LyP exclusively involving an irradiated area of the skin.

Lymphomatoid papulosis (LyP) is a clinicopathologic variant of CD30⁺ primary cutaneous T-cell lymphoproliferative disorder characterized by a chronic, recurrent, self-healing eruption of papules and small nodules. From a clinical point of view, LyP is not considered a malignant disorder despite demonstration of clonality in most cases.¹ From a histopathologic point of view, there are 5 types of LyP: (1) type A, the most common type, which is characterized by a wedge-shaped infiltrate composed of clustered large atypical cells admixed with neutrophils, eosinophils, histiocytes, and small lymphocytes; (2) type B, a rare variant characterized by a bandlike infiltrate of small- to medium-sized pleomorphic and hyperchromatic lymphocytes involving the superficial dermis with epidermotropism; (3) type C, which consists of a nodular infiltrate of large atypical cells with a cohesive arrangement closely similar to anaplastic large-cell lymphoma; (4) type D, a variant with histopathologic features that resemble primary cutaneous aggressive epidermotropic CD8⁺ cytotoxic T-cell lymphoma, but neoplastic cells express CD30 and a T-cell cytotoxic phenotype (βF1⁺, CD3+, CD4^‒, CD8⁺), and follow-up usually does not reveal development of systemic involvement or signs of other cutaneous lymphomas²; and (5) type E, which is characterized by oligolesional papules that rapidly ulcerate and evolve into large, necrotic, escharlike lesions with a diameter of 1 to 4 cm and an angiocentric and angiodestructive infiltrate of small- to medium-sized atypical lymphocytes expressing CD30 and frequently CD8.³

The clinical appearance of LyP usually is polymorphic, with lesions in different stages of evolution scattered all over the skin; however, the lesions are occasionally localized only to one area of the skin, the so-called regional or agminated LyP.^4-14 We report a case of regional LyP that exclusively involved the skin of the left breast, which had previously received radiotherapy for treatment of breast carcinoma. Lymphomatoid papulosis with cutaneous lesions involving only an area of irradiated skin is rare.

Case Report

A 59-year-old woman presented with new-onset cutaneous lesions on the left breast. The patient had a history of invasive ductal carcinoma of the left breast, which had been treated 5 years prior with a partial mastectomy and radiotherapy (10 Gy per week for 5 consecutive weeks [50 Gy total]). Physical examination revealed a large nodular lesion with a necrotic surface on the upper half of the left breast as well as 3 small papular lesions with eroded surfaces on the lower half of the breast (Figure 1). A clinical diagnosis of cutaneous metastases from breast carcinoma was suspected.

Biopsies from one small papule and the large nodular lesion showed similar findings consisting of a necrotic epidermis covered by crusts and a wedge-shaped infiltrate involving the superficial dermis (Figure 2A). The infiltrate was mostly composed of large atypical mononuclear cells with oval to kidney-shaped nuclei, prominent nucleoli, and ample basophilic cytoplasm. Many mitotic figures were seen within the infiltrate (Figure 2B). The infiltrate of atypical cells was admixed with small lymphocytes, histiocytes, and some eosinophils. Immunohistochemically, the large atypical cells expressed CD2, CD3, CD4, CD45, CD30, and epithelial membrane antigen (Figures 2C and 2D). A few atypical cells also expressed CD8 and T-cell intracellular antigen 1. Approximately 60% of the nuclei of the atypical cells showed MIB-1 positivity, while CD20, CD56, AE1/AE3, S-100 protein, CD34, and CD31 were negative. The anaplastic lymphoma kinase was not expressed in atypical cells. Monoclonal rearrangement of the γ T-cell receptor was demonstrated on polymerase chain reaction. Physical examination showed no lymphadenopathy in any lymph node chains. Computed tomography of the chest and abdomen failed to demonstrate systemic involvement. On the basis of these clinical, histologic, immunohistochemical, and molecular results, a diagnosis of type A regional LyP was established.

The patient was treated with 2 daily applications of clobetasol propionate cream 0.5 mg/g and 10 mg of oral methotrexate per week for 4 weeks. After 4 weeks of treatment, the lesions on the left breast had resolved leaving slightly atrophic scars. Six months later, an episode of recurrent papular lesions occurred in the same area and responded to the same treatment, but no systemic involvement had been found.

Comment

Regional LyP is a rare variant, with only a few reported cases in the literature.^4-18 Scarisbrick et al⁴ originally reported 4 patients with LyP limited to specific regions. Interestingly, one of the patients had mycosis fungoides and the LyP lesions were confined to the same region where the mycosis fungoides lesions were observed.⁴ In a review of LyP in patients from the Netherlands (n=118), lesions limited to a specific region of the body were observed in 13% of cases.⁵ Cases of LyP limited to acral skin also have been reported.^6-8 Heald et al⁹ described 7 patients who had continuing eruptions of papulonodules with histopathologic features of LyP within well-circumscribed areas of the skin. The investigators interpreted this localized variant of LyP as an equivalent of the limited plaque stage of mycosis fungoides. Interestingly, one of the patients with LyP eventually developed plaques of mycosis fungoides in other areas of the skin not involved by LyP.⁹ Sharma et al¹⁰ described an additional example of regional LyP, and Nakahigashi et al¹¹ described a patient with tumor-stage mycosis fungoides who subsequently developed regional LyP involving the right side of the chest. Kim et al¹² described a patient with recurrent episodes of regional LyP exclusively involving the periorbital skin, and Torrelo et al¹³ reported a 12-year-old boy with persistent lesions of LyP involving the skin of the right side of the abdomen. Coelho et al¹⁴ reported a 13-year-old adolescent girl who presented with recurrent papules of LyP exclusively involving the left upper arm. Buder et al¹⁵ reported a case of LyP limited to Becker melanosis. Shang et al¹⁶ described an additional caseof regional LyP that was successfully controlled by interferon alfa-2b and nitrogen mustard solution. Haus et al¹⁷ reported type A LyP confined to the cutaneous area within a red tattoo. Finally, Wang et al¹⁸ reported a case of regional LyP in association with pseudoepitheliomatous hyperplasia

Several dermatoses may appear as specific isomorphic responses to various external stimuli, and it is possible that radiotherapy induces some damage that favors the location of the lesions because the irradiated skin behaves as a locus minoris resistentiae. Pemphigus vulgaris,^19,20 Sweet syndrome,²¹ cutaneous angiosarcoma,^22-32 and cutaneous metastases from malignant melanoma also have been reported to be confined to irradiated skin.³³ However, in our PubMed search of articles indexed for MEDLINE using the terms lymphomatoid papules and regional, none of the previously reported cases of regional LyP had a history of radiotherapy, and in no instance did the lesions develop on a previously irradiated area of the skin.^4-18 The localization of the lesions in our patient could have been the result of the so-called radiation recall phenomenon. Recall dermatitis is defined as a skin reaction in a previously irradiated field, usually subsequent to the administration of cytotoxic drugs or antibiotics.³⁴ It may appear days to years after exposure to ionizing radiation and has mostly been associated with chemotherapy drugs, but recall dermatitis is neither exclusive of chemotherapy medications nor strictly radiotherapy induced. The concept of recall dermatitis has been expanded beyond radiation recall dermatitis to include dermatitis induced by other stimuli, including other drugs, contact irritants, and UV radiation, as well as residual herpes zoster. Nevertheless, in recall dermatitis the triggering drug or agent recalls a prior dermatitis in the involved area, such as sunburn or radiodermatitis. In our patient, there was no history of LyP prior to irradiation of the left breast; therefore, the most plausible interpretation of the peculiar localization of the lesions in our patient seems to be that the eruption resulted as expression of a locus minoris resistentiae.

Distinction between primary cutaneous anaplastic large-cell lymphoma and LyP may be difficult because the histopathologic and immunophenotypic features may overlap. In our case, the presence of several papular lesions and one large nodule are more consistent, from a clinical point of view, with a diagnosis of LyP rather than primary cutaneous anaplastic large-cell lymphoma, which usually presents with a solitary and often large, ulcerated, reddish brown tumor. In our patient, the absence of lymphadenopathy, negative results of the computed tomography of the chest and abdomen, and lack of expression for anaplastic lymphoma kinase in atypical cells of the infiltrate militate against a diagnosis of secondary cutaneous involvement from nodal disease.

The histopathologic differential diagnosis of the current case also included cutaneous CD30⁺ epithelioid angiosarcoma of the breast. Weed and Folpe³⁵ reported the case of an 85-year-old woman who developed a CD30⁺ epithelioid angiosarcoma on the breast after undergoing breast-conserving surgery and adjuvant radiotherapy for treatment of an infiltrating ductal carcinoma of the breast. Histopathology showed a diffuse replacement of the dermis by a highly malignant-appearing epithelioid neoplasm growing in a solid sheet. Neoplastic cells expressed strong CD30 immunoreactivity with absence of immunoexpression for cytokeratins, S-100 protein, and CD45. Additional immunostaining demonstrated that neoplastic cells also expressed strong immunoreactivity for CD31 and the friend leukemia virus integration 1 gene, FLI-1, and focal positivity for von Willebrand factor, supporting a diagnosis of epithelioid angiosarcoma.³⁵ In our patient, CD34 and CD31 were negative, which ruled out the endothelial nature of neoplastic cells.

Conclusion

In summary, we report an example of regional LyP limited to the left breast of a woman with a history of partial mastectomy and adjuvant radiotherapy for treatment of invasive ductal breast carcinoma. It is a rare case of regional LyP exclusively involving an irradiated area of the skin.