ABSTRACT
Plexiform neurofibroma is a benign proliferation that arises from the peripheral nerves and represents one of the diagnostic features of neurofibromatosis type I (NF-1). They are commonly found in the gastrointestinal tract, and intrathoracic neurofibroma is relatively uncommon. Ultimately, this tumor grows along the length of any single nerve and may involve multiple fascicles or branches of major nerves. Here, we report a case of multiple-site plexiform neurofibromas in a 40-year-old man previously diagnosed with NF-1. Although he had no perceptible symptoms, contrast-enhanced CT revealed massive diffuse neurofibromas that involved the mediastinum, periportal region, retroperitoneal space, and the mesentery. Histopathological studies of the neck, skin, and intra-abdominal soft tissue showed loose spindle cells and collagen bundles. The microscopic appearance was typical of a plexiform-type neurofibroma. It was decided that we would observe the patient without surgical management, because the neurofibromas were asymptomatic.