A case of malignant peripheral sheath tumor arising from neurofibromatosis type 1

Malignant peripheral nerve sheath tumor (MPNST) is a term encompassing tumors previously diagnosed as malignant schwannoma, malignant neurilemmoma, neurogenic sarcoma, and neurofibrosarcoma The occurrence rate of MPNST in neurofibromatosis type 1 patients is known to be about 4.6%. Tumors occurring in this particular group have a worse prognosis in that they occur at an earlier age, are more centrally located, tend to be of a larger size and show more metastases and recurrences. We present a typical case of MPNST in a 36-year-old man with NF type 1, which occurred on the left buttock. A PET-CT showed findings of possible inguinal lymph node metastasis and a lymph node biopsy confirmed the diagnosis. The patient was treated with wide surgical resection and is undergoing adjuvant radiation therapy.