Excavated Duodenal Gastrointestinal Stromal Tumor (Gist) Diagnosed By Standard Endoscopic Biopsy

Introduction: An 83-year-old man presented with 1 month of slow gait associated with 2 weeks of fevers and weakness. He also reported a near syncopal episode associated with chest pain prior to admission. Physical exam revealed a systolic murmur and right upper quadrant abdominal tenderness. His blood work was notable for leukocytosis and an ESR of 102. Transthoracic echocardiogram showed 14mm linear echodensity on the aortic valve. A follow-up transesophageal echocardiogram did not show any evidence of vegetations. Computed tomography of the chest, abdomen and pelvis revealed a 4cm enhancing heterogeneous lesion thought to be in the head of the pancreas. Esophagogastroduodenoscopy with endoscopic ultrasound (EGD-EUS) showed a 3cm lesion in the second portion of the duodenum with a deep excavated necrotic center that was easily friable. There was no evidence of pancreatic mass on EUS. Multiple jumbo biopsies were taken from the edge of excavation using standard endoscopic technique, which showed duodenal mucosa with submucosal proliferation of uniform bland spindle cells with anuclear areas diffusely positive for CD117, negative for S-100, which was compatible with gastrointestinal stromal tumor (GIST). The patient underwent a Whipple procedure, which demonstrated that the GIST did not invade the duodenal mucosa or pancreas on pathology. C-Kit mutation was detected on genetic sequence analysis. This clinical vignette demonstrates a rare case of a duodenal GIST that was diagnosed by standard endoscopic biopsy. Typically, endoscopic forceps do not yield enough tissue for a definitive diagnosis. EUS with fine needle aspiration provides better results with one study showing up 82% sensitivity and 100% specificity for diagnosis of GIST. GISTs occurring in the duodenum represent only approximately 5% of all GISTs as well as 10% to 30% of all malignant duodenal tumors. GISTs are most commonly found in the stomach, accounting for 60-70% of all cases. The clinical presentation of GISTs ranges from incidental discovery on endoscopy to nonspecific symptoms or overt GI bleeding. Interestingly, our patient presented with features suggestive of endocarditis, which were subsequently found to be secondary to the duodenal GIST.Figure 1: Excavated duodenal GIST with necrotic center.