Histopathological features of flexural melanocytic nevi: a study of 40 cases

Melanocytic nevi in certain locations such as the genital and acral sites m ay have atypical histologic features simulating melanoma. We studied the mi croscopic findings of 40 melanocytic nevi of flexural sites (axilla, umbili cus, inguinal creases, pubis, scrotum and perianal area) to Verify if flexu ral nevi show distinctive features similar to melanocytic nevi of the genit al skin. The patients were young (mean age 20 years), the lesions were most ly removed for cosmetic reasons and we are not aware of any deaths or compl ications related to the removed nevi. We found that 22 (55.5%) out of 40 fl exural nevi had "a nested and dyshesive pattern" similar to the melanocytic nevi of genital skin. This pattern was characterized by the confluence of enlarged nests with variation in size, shape and position at the dermoepide rmal junction and by the diminished cohesion of melanocytes. Dermatopatholo gists should pay attention to the "nested and dyshesive pattern" of flexura l nevi that may mimick hystologic changes of melanoma.