PERPLEXING PIGMENTED PAPULES SIMULATING MALIGNANT-MELANOMA

The clinical presentation of irregularly pigmented papules raises a spectrum of diagnostic possibilities. An eighty-five-year-old black man was referred for evaluation of lesions of fifty years' duration. The lesions were 1 to 2 cm hyperkeratotic, irregularly darkly-pigmented papules limited to sun-exposed areas. The histopathologic findings of large keratinocytes, acanthosis, hypergranulosis, and orthokeratosis were compatible with a diagnosis of large cell acanthoma. We believe large cell acanthoma should be included in the differential diagnosis of keratotic or irregularly pigmented lesions on sun-exposed skin, even in black patients.