Metastatic melanoma to the skin simulating blue nevus

Cutaneous metastases from melanoma can mimic primary melanoma and melanocyt ic nevi. Recognition of a metastatic lesion is of great importance for prop er staging and treatment decisions. In this study, a potential diagnostic p itfall is described and discussed: dermal metastases from cutaneous melanom a simulating blue nevus, a phenomenon that has received little attention. T en blue nevus-like lesions from three patients are presented. All contained pigmented melanocytes and melanophages in variable proportions arranged in a blue nevus-like growth pattern. The blue nevus-like metastases occurred in the same anatomic region as the primary tumor or, as in one patient, nea r the skin scar of a dissected lymph node metastasis. Histologic clues of m etastatic melanoma included the presence of atypical epithelioid melanocyte s, mitotic figures, and an associated inflammatory cell infiltrate at the p eriphery of the lesion. Although such histologic features facilitate the re cognition of a metastasis, clinical correlation is essential for a definiti ve diagnosis.