Malignant peripheral nerve sheath tumor: a study of 21 cases

Malignant peripheral nerve sheath tumor (MPNST) is an aggressive tumor of neural origin. To improve our experience with this rare tumor, we reviewed 21 patients seen during a 12-year period at the pathological department of Taichung Veterans General Hospital.

Clinical data including age, sex, presence or absence of von Recklinghausen's disease, tumor location and size, presenting symptoms, surgical management and surveillance were summarized. Microscopically, we examined necrosis, mitosis, differentiation, the resection margin, and the presence or absence of neurofibromatous component.

There were 15 males and 6 females with age range of 9-86 years. Seven cases were associated with neurofibromatosis and 14 cases were solitary MPNST: Patients with coexistent neurofibromatosis were younger (mean age at diagnosis, 32 years) than patients with solitary MPNST (mean, 60.2 years). Tumors of the former group tended to be centrally located. Anaplastic alteration was found in the recurrent tumors of two patients both of whom died of the disease. Of the 21 cases, epithelioid differentiation and osteoid metaplasia were seen in two tumors respectively by optical microscopy. Patients with von Recklinghausen's disease and large incompletely resected tumors had the most dismal prognosis. Of five patients with neurofibromatosis who were observed for more than two years, only one survived and no recurrence was found. The remaining four patients died within 3-9 months. However, of 14 cases of solitary MPNST, only two patients died of disease and ten of them had survived beyond two years.

Our work revealed that patients with von Recklinghausen's disease, a large unresectable centrally located tumor with diffuse anaplastic alteration, had frequent recurrences and poor prognosis. Aggressive surgical procedure with free resection margin is suggested. Malignant transformation should be highly suspected when a painful, rapidly growing tumor developed.