Acral melanocytic neoplasms: a histologic analysis of 158 lesions.

BACKGROUND: Acral nevi occasionally demonstrate pagetoid spread of melanocytes. This feature may be of considerable concern because it is commonly associated with melanoma. Other features of melanoma must be assessed to accurately classify these neoplasms as benign.

OBJECTIVE: We examined acral melanocytic lesions, benign and malignant, to evaluate their features.

METHODS: A retrospective analysis during 3 years was performed on 158 acral pigmented lesions diagnosed by the dermatopathology service. Blue nevi, intradermal nevi, lentigines, and Spitz nevi were excluded. The specimens were divided into three groups: benign nevi, benign nevi with pagetoid spread, and melanoma. They were evaluated for circumscription, symmetry, papillary dermal fibroplasia, bridging between rete ridges, inflammatory infiltrate, pagetoid spread, cytologic atypia, and mitotic activity.

RESULTS: Most lesions (60%) were compound nevi and 84% were from the foot. Ten specimens were melanomas (6%) and 28 (18%) were nevi with architectural disorder. Pagetoid spread of melanocytes, often minimal, was found in 57 benign lesions. However, these nevi did not demonstrate the degree of pagetoid spread, cellular atypia, inflammation, and asymmetry found in malignant lesions.

CONCLUSIONS: The presence of pagetoid spread of melanocytes is common in otherwise benign acral nevi. Other parameters of malignancy in these neoplasms must be evaluated to determine their biologic potential.