Recurrent pigmented melanocytic nevus. A benign lesion, not to be mistaken for malignant melanoma.

Melanocytic nevi that recur after incomplete removal are pigmented lesions that may clinically and pathologically simulate malignant melanoma in situ. Five examples of recurrent pigmented melanocytic nevus, with emphasis on light microscopic and immunohistochemical findings, are reported herein. Prominent HMB-45 staining in these nevi may cause further confusion in differentiating them from malignant melanoma. The differential diagnosis of recurrent pigmented melanocytic nevi is discussed, with particular emphasis on distinguishing these lesions from malignant melanoma. Our immunohistochemical observations indicate that the recurrences most likely develop as a result of proliferation of melanocytes remaining in the epidermis and/or adnexae following incomplete removal. The approach and management of recurrent nevi are also discussed.