De novo intraepidermal epithelioid melanocytic dysplasia as a marker of the atypical mole phenotype -- a clinical and pathological study of 75 patients.

BACKGROUND: We encountered a distinctive pattern of dysplastic intraepidermal melanocytic proliferation, which defies classification as a dysplastic melanocytic nevus, but in which the morphologic features fall short of a diagnosis of melanoma in situ. We designate such lesions as de novo intraepidermal epithelioid melanocytic dysplasia.

METHODS: From 75 patients, 82 skin biopsies were encountered that showed this distinctive morphology. Hematoxylin- and eosin-stained histologic sections were studied and the features were correlated with personal and family histories of dysplastic nevi and melanoma.

RESULTS: The diagnosis of de novo melanocytic dysplasia was made in 27 male patients and 48 female patients (mean age: 44 years). The histologic hallmark was a pagetoid (single-cell) array of moderately to severely atypical epithelioid melanocytes within the epidermis. Seventy-three lesions were located on sun-exposed skin and nine on sun-protected skin. In 41 patients, there was an atypical mole phenotype, whereas 20 patients had a prior or subsequent diagnosis of melanoma with five of 16 patients questioned revealing a family history of melanoma.

CONCLUSIONS: De novo intraepidermal epithelioid melanocytic dysplasia is a distinct entity associated with an atypical mole phenotype and a personal and/or family history of melanoma.