Eccrine-Centric Melanocytic Nevus.

Benign melanocytic neoplasms present with a diverse array of well-known histopathologic patterns. It is imperative to recognize the benign patterns to render accurate diagnoses. We describe here an interesting and hitherto not described low-power architectural pattern of a benign melanocytic lesion: eccrine-centric melanocytic nevus. The patient was a 50-year-old African American woman who noticed a new mole on her foot that began as a dark speck but quickly grew larger. The lesion was excised to exclude the possibility of melanoma. Upon review of the specimen, the lesion was noted to demonstrate a distinctive pattern consistent with a melanocytic nevus of possible congenital onset. Remarkably, the ducts of eccrine glands were increased in density and the nests of melanocytes were found solely in a peri-eccrine distribution without melanocytes in any other locations (ie, interstitial, perifollicular). Additionally, all melanocytes in the nevus were rather heavily pigmented. Although this pattern demonstrated no atypical features that would cause one to consider it malignant to the trained eye, this presentation could implicate a metastatic disease (well-delineated nests in the dermis without concomitant interstitial component) and it is important to recognize.