A case of bathing trunk nevus studded with neurofibroma-like papules.

There is a significant association between bathing trunk nevus and neurofibromatosis. However, not all neurofibroma-like papules detected clinically in cases with bathing trunk nevus may be a neurofibromas and histopathological confirmation is essential for definition of these lesions. We report a 21 year old white male patient with a bathing trunk nevus studded with neurofibroma-like papules of melanocytic nature. Histopathological examination of both papular and flat lesions showed diffuse melanocytes with plentiful eosinophilic cytoplasm and round nuclei in the dermis. Immunohistochemistry showed strong positivity of dermal melanocytes for S-100 protein. The clinical and histopathological findings and positivity of dermal melanocytes for S-100 protein were consistent with bathing trunk melanocytic nevus.