2617 Duodenal Leiomyosarcoma: A Rare Cause of Gastric Outlet Obstruction

Abstract

INTRODUCTION: Intestinal leiomyosarcoma (LMS) is a rare cancer comprising 0.2% of all malignant tumors and involves the ileum in nearly half of cases. The remainder occur in the proximal duodenum and jejunum primarily, or metastatically from non-intestinal sites such as the uterus. We report this case of primary duodenal LMS complicated by gastric outlet obstruction. CASE DESCRIPTION/METHODS: A 57 year old woman presented with a two month history of worsening epigastric and right upper quadrant pain without nausea, vomiting, weight loss, or altered bowel habits. On physical exam she had marked epigastric tenderness. Abdominal contrast CT demonstrated multiple hypodense liver lesions measuring up to 2cm and a mildly dilated and thickened descending segment of the duodenum. Laboratory evaluation including tumor markers was normal. Without a clear primary malignancy source, the patient underwent percutaneous liver biopsy. Histopathology revealed high grade smooth muscle sarcoma, which stained positively for desmin, SMA, CD 57, and CD 34. Chemotherapy with gemcitabine and docetaxel was initiated per oncology. Within weeks, the patient developed worsening abdominal pain, nausea, and vomiting. CT imaging showed a mass projecting over the descending duodenum causing gastric outlet obstruction. After nasogastric decompression, the patient underwent an EGD. A friable, circumferential mass was seen emanating from distal duodenal bulb extending proximally to the second portion. A duodenal self expanding metal stent was inserted from just proximal to the ampulla to the distal antrum, effectively bridging the mass. Biopsy of the mass was consistent with high grade sarcoma, identical to the liver biopsy. Upper GI contrast series confirmed stent patency; patient tolerated an appropriately advanced diet, and was discharged home to continue outpatient chemotherapy. DISCUSSION: Based on our literature review, there have been no documented cases of gastric outlet obstruction secondary to duodenal LMS. Such tumors often present with abdominal pain and bleeding due to their highly vascular nature. In general, small intestinal malignancies are rare and often difficult to diagnose due to non-specific symptomatic progression resulting in delayed evaluation. Disease is often advanced to lymphatic spread or metastasis at diagnosis as was the case in our patient. A broad differential diagnosis should be considered in patients with unclear primary malignancies presenting with obstructive symptoms.