Case of pigmented neurofibroma with hypertrichosis with no association to neurofibromatosis.

Pigmented neurofibroma (PNF) is a rare cutaneous tumor that has been observed in patients with or without neurofibromatosis (NF). This tumor is histologically characterized by the coexistence of scattered melanin-laden cells and benign spindle cells with neural differentiations. Hypertrichosis is the excessive growth of hair on non-androgen-dependent areas of the body. It has been reported that hypertrichosis may sometimes overlie a neurofibroma. We highlight a case of PNF with hypertrichosis on a 17-year-old woman with no associated NF. We also discuss the possible underlying pathogenic mechanism of a localized hypertrichosis in PNF patients.