1609 Spontaneous Perforation of a Sigmoid Gastrointestinal Stromal Tumor

Abstract

INTRODUCTION: Most gastrointestinal stromal tumors (GISTs) are asymptomatic and involve the stomach and small intestine. Spontaneous rupture of a large sigmoid GIST is an exceptionally rare complication. Only three other cases of sigmoid perforation due to a GIST were described in literature. CASE DESCRIPTION/METHODS: A 90-year-old male with acutely worsening lower abdominal pain underwent emergent bowel resection for presumptive colonic perforation secondary to sigmoid diverticulitis. Initial abdominal computed tomography (CT) showed wall thickening in the sigmoid colon as well as an air-containing interloop heterogeneous mass measuring 3.5 × 2.0 cm with free intraperitoneal air. Laparotomy thereafter revealed a mass at the perforation site which was resected. Histopathologic examination revealed an infiltrative high-grade spindle cell neoplasm with marked cellular atypia, involving the muscularis propria and submucosa with extension to the adjacent pericolonic fat. CD117 (C-kit), CD34 and DOG1 biomarkers were negative, as well as actin, desmin, keratin and S100 stains. Hence, the diagnosis of a dedifferentiated KIT-negative GIST was made based on the favorable histopathology of the tumor via a consensus from the pathology department. DISCUSSION: Spontaneous bowel perforation, particularly in the sigmoid colon, is an exceedingly rare complication of GIST. Immunohistochemical studies can confirm the diagnosis; however, the absence of positivity for biomarkers does not exclude it in which case consensus from the pathology department is required to confirm the diagnosis. Physicians need to be cognizant of the propensity for GISTs to lead to bowel perforation, including the sigmoid colon.