S1957 Perforated Colonic GIST: A Rare Cause of Acute Abdomen

Abstract

Introduction: Gastrointestinal stromal tumors (GISTs) are the most common connective tissue neoplasms of the gastrointestinal (GI) tract, usually found in the stomach and small intestine. Approximately 10-30% of patients with this malignancy are asymptomatic. Historically, GISTs have been discovered incidentally as patients often present with nonspecific symptoms such as abdominal pain, nausea, and weight loss. Most patients present with symptoms when the tumor grows >5 cm or with acute complications such as perforation or acute peritonitis. We report a rare case of acute abdomen secondary to a perforated colonic GIST treated by surgical resection and chemotherapy. Case description/methods: A 59-year-old female with hypertension and diabetes mellitus presented with abdominal discomfort for one day, associated with episodes of non-bilious, non-bloody emesis. She denied hematemesis, hematochezia, melena, weight loss, and changes to her bowel habits. Physical examination demonstrated diffuse abdominal tenderness without rigidity or guarding. Initial laboratory investigations revealed a leukocyte count of 17.2 × 103/uL. A computed tomography (CT) scan of the abdomen and pelvis without contrast demonstrated pneumoperitoneum. She was taken to the OR for an emergent exploratory and underwent Hartman’s procedure for a perforated colon. Pathology of the surrounding tissue revealed a high-grade GIST (positive for CD117, KI-67 value of 30%, and mitotic index > 5). Patient was started on Imatinib therapy. A subsequent CT scan five months after discharge revealed several new subcapsular liver masses, the largest measuring 2.6 × 2.2 cm along the falciform ligament and ascites in the left paracolic space. The patient follows with Oncology in outpatient clinic. Discussion: GISTs comprise < 3% of all gastrointestinal tumors and are associated with high rates of malignant transformations. While imagine modalities aid in identification, definitive diagnosis requires histopathological examination. Approximately 95% of GISTs express CD117, a component of the cKIT tyrosine kinase receptor, as in our patient. As majority of GISTs are found in the stomach and small intestine, it is very uncommon for this malignancy to manifest in the colon. Furthermore, it is extremely rare for GISTs to cause perforation and acute peritonitis. Clinical outcome in these cases is dependent on early identification and prompt intervention. While GISTs are rare, providers must consider this diagnosis when visualizing abnormal masses with perforations.