Case Presentation A 67-year-old white man presented with a 6-month history of a slowly increasing in size, slightly pruritic, erythematous rash in his right lower abdominal quadrant extending to his inguinal fold and right side of his scrotum. He reported having a similar lesion in his right axilla 7 years earlier that was surgically excised with no clinical evidence of recurrence. Otherwise, he was healthy with no history of systemic diseases. On examination there was an 8-cm by 6-cm erythematous, slightly elevated, papillomatous plaque extending from his right pubic area to the right lateral scrotal wall. No alopecia was noted overlying the plaque. No inguinal lymphadenopathy was appreciated on nodal examination. A well-healed scar was present in the right axilla, but no axillary adenopathy was noted. A KOH preparation of the lesion was negative for hyphae. Histologic examination of a 4-mm punch biopsy specimen taken from the inguinal plaque revealed an atypical cellular proliferation composed of clear cells ascending through the epidermis. These cells were positive for carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA) and mucicarmine stains. The S-100 stain did not stain these cells. What’s Your Diagnosis? Turn to page 98 for an answer and for more details.