Malignant peripheral nerve sheath tumors arising from ganglioneuromas.

Two typical malignant peripheral nerve sheath tumors (PNST) arising in preexisting ganglioneuromas are described. To the best of our knowledge, this association of tumors has not been reported in detail previously. Neither patient had the stigmata nor family history of Von Recklinghausen's neurofibromatosis. In both cases, the ganglioneuromas evolved from more primitive neuroectodermal tumors (one neuroblastoma, one ganglioneuroblastoma) and both patients developed their malignant PNST at previously irradiated sites. Both patients died within 2 years of the diagnosis of their malignant PNST. The origin of these malignant PNSTs from Schwann cells is supported by an ultrastructural analysis of 27 neuroblastomas, ganglioneuroblastomas, and ganglioneuromas.