Plexosarcoma: endoscopic ultrasound and electron-microscopic characteristics of a stromal tumor

Endoscopic ultrasound is useful for managing submucosal masses; however, some of these lesions can be difficult to classify except with full histological and electron microscopic evaluation. A 72-yr-old woman was seen with upper GI bleeding. Endoscopy showed a 1.7-cm sessile ulcerated submucosal mass in the duodenal bulb. Endoscopic ultrasound revealed an echolucent submucosal mass arising from the fourth echolayer, the muscularis propria of the duodenal wall. These findings suggested that the lesion was a leiomyoma. The patient eventually had the lesion resected because of recurrent bleeding. Histologically it was a spindle cell tumor that on electron microscopy showed neuronal elements consistent with a plexosarcoma, or gastrointestinal autonomic nerve tumor. These lesions account for some one third of all gastrointestinal stromal tumors. Despite their low grade malignant histologic appearance, local recurrence or hepatic metastases occur in about 70% of patients.