ABSTRACT
Diagnosis Diagnosis is usually suspected by a mass lesion. Approximately one-half to two-thirds of all patients with MPNST will be seen in association with an underlying neurofibroma. This explains the high prevalence of patients with neurofibromatosis as the background to the development of MPNST. Most patients are between 20 and 40 years of age at the time of onset. The tumors are uncommon in children. Patients with neurofibromatosis-1 (NF-1) usually develop tumors at an earlier age. Patients present with a firm to hard mass, often with some central necrosis. Histologic patterns (see Chapter 3) are diverse: various subtypes have been described, including the epithelioid type, the malignant triton tumor, usually reserved for the peripheral nerve tumor that has rhabdomyosarcomatous differentiation.
