Abstract

Clear Cell Acanthoma (CCA) is a benign epidermal tumor commonly seen on the lower extremities of middle-aged-men. To the best of our knowledge, only one case of perianal CCA (PCCA) has been reported in literature of an elderly female with history of longstanding nonresponsive gluteal cleft psoriasis.

We present the second case of PCCA. A 58 year old Caucasian male presented to dermatology clinic with a 2 years history of intermittent, non-healing, ill-defined erythematous rash in the gluteal cleft, nonresponsive to topical steroids. Also a 30 years history of recurrent pilonidal cysts in the area requiring several surgical intervention, with last surgery being 15 years ago was noted. A punch biopsy revealed psoraosifrom epidermal hyperplasia with extensive clear cell change in keratinocytes. A confluent overlying parakeratosis, neutrophilic exocytosis with rare eosinophils and plasma cells were seen. PAS staining demonstrated no fungal organisms and stained clear cell keratinocytes supporting presence of intracellular glycogen. Gram stain and CK-7 were negative. HSV-PCR testing performed on wound swab was negative. The final diagnosis of psorasiform dermatitis was favored over histological diagnosis of clear cell acanthoma (CCA) due to clinical history. Patient was given oral antibiotics, topical steroids and antibiotic ointment. Patient reported only slight improvement. A repeat biopsy several months later revealed psorasiform epidermal hyperplasia with cytoplasmic clearing and neutrophils exocytosis once again favoring CCA diagnosis histologically.

This case extend the differential diagnosis of perianal lesion to include PCCA, along with proposing a surgical intervention as a definitive management options for these patients.