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Prompted by his new bride, who is concerned she might “catch something” from him, a 53-year-old man self-refers for evaluation of a slightly itchy intergluteal rash. He’s had it for years; it waxes and wanes but never fully resolves.
It has been previously diagnosed as a yeast infection, fungal infection, and even herpes. But none of the respective treatments have helped.
More history-taking reveals a family history of psoriasis (maternal grandmother), but the patient denies other areas of involvement or other skin changes. He also denies having arthritis.
EXAMINATION
A salmon-pink, 7-cm, roughly round dry patch covered by white tenacious scale is located in the upper intergluteal/sacral interface. There is no increased warmth or tenderness on palpation.
A similar process is noted in the periumbilical area (a difficult area for this patient to see, due to his weight). Inspection of his fingernails reveals 3/10 with definite tiny pits.
What is the diagnosis?
DISCUSSION
The urge to call any and every rash occurring near the genitals a yeast infection is universally compelling among primary care providers. It is often so reflexive that even when anti-yeast medications fail, the provider hangs onto the diagnosis. This happens for one simple reason: Their differential is lacking.
This patient has psoriasis, albeit a somewhat unusual form, which demonstrates an important learning point: Psoriasis can present in any number of ways, not just in the standard “extensor surfaces of elbows and knees” distribution. It’s not unusual for psoriasis to zero in on one or two areas. I’ve seen it confined to the groin, the genitals, and the scalp. It can even involve the oral mucosa.
In these somewhat obscure cases, additional findings can be helpful to establish the diagnosis. The two areas of involvement in this case—the upper intergluteal area and the periumbilical region—may not fit the classic “knees and elbows” picture of psoriasis, but they are not atypical for the disease. Add the nail pits, the fixed nature of the problem, and the family history, and you’ve nailed the diagnosis.
Don’t forget that, occasionally, psoriatic arthropathy can precede the appearance of psoriasis, and that the severity of one does not predict the severity of the other.
Finally, in a fair number of cases, the diagnosis of psoriasis must be made by biopsy, which shows characteristic changes such as parakeratosis, epidermal thickening, and fusing of rete ridges. These “psoriasiform” changes seen microscopically must be corroborated by clinical findings, though, since many other papulosquamous diseases can exhibit similar changes.
TAKE-HOME LEARNING POINTS
- Psoriasis is one of the more common dermatoses in this country, which means you will see it with some frequency.
- Psoriasis can affect limited or atypical areas, but corroboration of the diagnosis can be sought in classic areas (nails, scalp, upper intergluteal and periumbilical areas).
- Strive to develop alternative diagnoses for similar rashes—in other words, build your differential for “yeast infection.”
Prompted by his new bride, who is concerned she might “catch something” from him, a 53-year-old man self-refers for evaluation of a slightly itchy intergluteal rash. He’s had it for years; it waxes and wanes but never fully resolves.
It has been previously diagnosed as a yeast infection, fungal infection, and even herpes. But none of the respective treatments have helped.
More history-taking reveals a family history of psoriasis (maternal grandmother), but the patient denies other areas of involvement or other skin changes. He also denies having arthritis.
EXAMINATION
A salmon-pink, 7-cm, roughly round dry patch covered by white tenacious scale is located in the upper intergluteal/sacral interface. There is no increased warmth or tenderness on palpation.
A similar process is noted in the periumbilical area (a difficult area for this patient to see, due to his weight). Inspection of his fingernails reveals 3/10 with definite tiny pits.
What is the diagnosis?
DISCUSSION
The urge to call any and every rash occurring near the genitals a yeast infection is universally compelling among primary care providers. It is often so reflexive that even when anti-yeast medications fail, the provider hangs onto the diagnosis. This happens for one simple reason: Their differential is lacking.
This patient has psoriasis, albeit a somewhat unusual form, which demonstrates an important learning point: Psoriasis can present in any number of ways, not just in the standard “extensor surfaces of elbows and knees” distribution. It’s not unusual for psoriasis to zero in on one or two areas. I’ve seen it confined to the groin, the genitals, and the scalp. It can even involve the oral mucosa.
In these somewhat obscure cases, additional findings can be helpful to establish the diagnosis. The two areas of involvement in this case—the upper intergluteal area and the periumbilical region—may not fit the classic “knees and elbows” picture of psoriasis, but they are not atypical for the disease. Add the nail pits, the fixed nature of the problem, and the family history, and you’ve nailed the diagnosis.
Don’t forget that, occasionally, psoriatic arthropathy can precede the appearance of psoriasis, and that the severity of one does not predict the severity of the other.
Finally, in a fair number of cases, the diagnosis of psoriasis must be made by biopsy, which shows characteristic changes such as parakeratosis, epidermal thickening, and fusing of rete ridges. These “psoriasiform” changes seen microscopically must be corroborated by clinical findings, though, since many other papulosquamous diseases can exhibit similar changes.
TAKE-HOME LEARNING POINTS
- Psoriasis is one of the more common dermatoses in this country, which means you will see it with some frequency.
- Psoriasis can affect limited or atypical areas, but corroboration of the diagnosis can be sought in classic areas (nails, scalp, upper intergluteal and periumbilical areas).
- Strive to develop alternative diagnoses for similar rashes—in other words, build your differential for “yeast infection.”
Prompted by his new bride, who is concerned she might “catch something” from him, a 53-year-old man self-refers for evaluation of a slightly itchy intergluteal rash. He’s had it for years; it waxes and wanes but never fully resolves.
It has been previously diagnosed as a yeast infection, fungal infection, and even herpes. But none of the respective treatments have helped.
More history-taking reveals a family history of psoriasis (maternal grandmother), but the patient denies other areas of involvement or other skin changes. He also denies having arthritis.
EXAMINATION
A salmon-pink, 7-cm, roughly round dry patch covered by white tenacious scale is located in the upper intergluteal/sacral interface. There is no increased warmth or tenderness on palpation.
A similar process is noted in the periumbilical area (a difficult area for this patient to see, due to his weight). Inspection of his fingernails reveals 3/10 with definite tiny pits.
What is the diagnosis?
DISCUSSION
The urge to call any and every rash occurring near the genitals a yeast infection is universally compelling among primary care providers. It is often so reflexive that even when anti-yeast medications fail, the provider hangs onto the diagnosis. This happens for one simple reason: Their differential is lacking.
This patient has psoriasis, albeit a somewhat unusual form, which demonstrates an important learning point: Psoriasis can present in any number of ways, not just in the standard “extensor surfaces of elbows and knees” distribution. It’s not unusual for psoriasis to zero in on one or two areas. I’ve seen it confined to the groin, the genitals, and the scalp. It can even involve the oral mucosa.
In these somewhat obscure cases, additional findings can be helpful to establish the diagnosis. The two areas of involvement in this case—the upper intergluteal area and the periumbilical region—may not fit the classic “knees and elbows” picture of psoriasis, but they are not atypical for the disease. Add the nail pits, the fixed nature of the problem, and the family history, and you’ve nailed the diagnosis.
Don’t forget that, occasionally, psoriatic arthropathy can precede the appearance of psoriasis, and that the severity of one does not predict the severity of the other.
Finally, in a fair number of cases, the diagnosis of psoriasis must be made by biopsy, which shows characteristic changes such as parakeratosis, epidermal thickening, and fusing of rete ridges. These “psoriasiform” changes seen microscopically must be corroborated by clinical findings, though, since many other papulosquamous diseases can exhibit similar changes.
TAKE-HOME LEARNING POINTS
- Psoriasis is one of the more common dermatoses in this country, which means you will see it with some frequency.
- Psoriasis can affect limited or atypical areas, but corroboration of the diagnosis can be sought in classic areas (nails, scalp, upper intergluteal and periumbilical areas).
- Strive to develop alternative diagnoses for similar rashes—in other words, build your differential for “yeast infection.”
