2652 Primary Malignant Peripheral Nerve Sheath Tumor of Small Bowel and Colon Presenting With Metastases to Bone, Lung, Liver, Spleen, and Brain

Abstract

INTRODUCTION: Malignant Peripheral Nerve Sheath Tumor (MPNST) is a rare diagnosis, with an incidence of 1:100,000 per year and 4–10% of soft tissue sarcoma, contains properties both neural crest cells and mesenchymal cells. Gastrointestinal MPNSTs are rare disease conditions with only 10 cases reported worldwide in the literature. CASE DESCRIPTION/METHODS: A 71-year old Portuguese male, presented with 8-week history of abdominal pain, anorexia with 20Ib weight loss. Vital signs were normal. On physical examination, a firm, tender, fixed abdominal mass in the RLQ was palpated. CT scan of the abdomen showed a 10 cm necrotic mass on the right side of the abdomen with communication to the small bowel was detected with a suggestion of a walled off perforation. Colonoscopy revealed a flattening of the terminal ileum suggesting an extrinsic compression. Biopsy of tumor consisting of mixed spindle and pleomorphic cells with focal rhabdoid features, high grade nuclear features and brisk mitotic activity. A week later, he presented with symptoms of small bowel obstruction, the CT scan at this time showed a 8 cm left sided abdominal mass with communication to the small bowel with dilation of the jejunum suggesting a new partial obstruction in addition. The patient underwent a palliative debulking of the tumor. Multiple large obstructive masses were found in the Ligament of Treitz,significant portion of the small bowel, right colon, left upper quadrant and omentum. For palliation purposes, these masses were resected and anastomosis was performed. Gross examination of the surgical specimens revealed grayish-tan cystic masses filled with brownish tan hemorrhagic material. Histology of the masses were similr to previous mass. On immunohistochemistry, showed patchy weak S100 immunoreactivity and focal BCL-2 and Neuron Specific Enolase stain immunoreactivity. Ki-67 proliferation index was 70%. The pathologic diagnosis of MPNST was established. He developed multiple bone, pulmonary, liver, splenic and hemorrhagic brain metastases. He died under hospice care within six months of his initial presentation. DISCUSSION: MPNST, occurs mostly in association with Neurofibromatosis Type 1 (8–13%). The tumor typically originates from the nerve sheaths of the major nerves in the extremities (40%), trunk/ retroperitoneal (38%) and head and neck region (21%). However, recent case reports have also documented MPNST of the liver, thyroid gland, skin, eighth cranial nerve and rarely the greater omentum without a history of radiation or NF1.