Melanocytic nevi are associated with neurofibromas in neurofibromatosis, type I, but not sporadic neurofibromas. A study of 226 cases

Background: Neurofibromatosis, type 1, is associated with cutaneous melanin pigmentation, but an association with ordinary melanocytic nevi has not been described. Methods: This retrospective case‐control study was designed to see if neurofibromas in patients with neurofibromatosis, type 1 (NF‐1) differ from sporadic neurofibromas (SN) in their incidence of associated melanocytic nevi and other histologic features. Slides from 114 NF‐1 were compared with 112 SN and 300 intradermal melanocytic nevi (IDN). Results: Small lentiginous melanocytic nevi were identified over 13 NF‐1 (11%) but no SN (P = 0.0002). Compared with other NF‐1, NF‐1 with nevi were more frequently associated with melanocytic hyperplasia, giant melanosomes and diffuse neurofibroma (P