April 2002: 35-year-old healthy man with enlarging right parotid mass

The April 2002 Case of the Month (COM). 35-year-old healthy man developed a mass in the right parotid gland. A superifical parotidectomy was performed for a 4.5 x 1.5 x 1.5 cm mass involving the intraparotid facial nerve. Grossly the tumor was multinodular, smooth and yellow with normal surrounding salivary gland. Microscopically, the tumor showed expanding nodules composed of proliferating fibroblasts, Schwann cells, and perineural-like cells in a myxoid stroma. Normal peripheral nerve twigs were identified in the periphery of the tumor. There was no increased mitotic activity, cellularity or nuclear pleomorphism. S-100 immunohistochemical stain was positive. The tumor was diagnosed as a solitary plexiform neurofibroma. Plexiform neurofibromas in this area have been described in children with von Recklinghausen's disease or neurofibromatosis 1 (NF 1). Plexiform neurofibromas typically involve deep seated nerve trunks and is considered pathognomonic for NF 1. This unusual case represents a solitary variant of plexiform neurofibroma presenting as a parotid mass in an adult patient without a personal stigmata or family history of NF 1.