Neurofibromas

Abstract

Neurofibroma is the second most common and most prevalent peripheral nerve tumor. It arises from the Schwann cells of the peripheral nerve sheath but also comprises fibroblasts, perineural cells, and mast cells in a variably myxoid background. There are three typical forms of neurofibroma with a few subtypes: (1) localized neurofibroma (cutaneous and intraneural), usually not interfering with the remaining axons; (2) diffuse neurofibroma, an ill-defined form with growth pattern involving the infiltration of the adjacent subcutaneous tissues; and (3) plexiform neurofibroma, irregular cylindrical or fusiform enlargement of a nerve with the macroscopic appearance of the “bag of worms.” Massive soft tissue neurofibroma is a subtype causing elephantiasis neuromatosa with the underlying plexiform and diffuse components. Neurofibroma is typically sporadic, but in 10% of cases, it occurs syndromically in the course of neurofibromatosis 1 (NF1) (usually the plexiform neurofibroma). The deletion in the NF1 gene is responsible for the tumor development in both sporadic and syndromic cases. The lesions are usually in the form of palpable mass and cause no specific symptoms. Diagnostic evaluation includes ultrasound and magnetic resonance imaging. Due to the benign nature, clinical follow-up is usually advised; however, in symptomatic cases, surgery is indicated. With adequate surgical approach, functional preservation is possible in the majority of cases, as is the pain control. Both reoccurrence and malignant transformation are rare in sporadic cases and more common in NF1-associated tumors. © The Editor(s) (if applicable) and The Author(s) 2021.