A Unique Case of Mesenteric Gastrointestinal Stromal Tumor Presenting as an Acute Abdomen.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the digestive tract and arise from the interstitial cells of Cajal in the mesenteric plexus. These tumors can originate in any part of the GI tract; however, a higher burden has been observed in the stomach and small intestines. Mesenteric GISTs are exceedingly rare, with unique clinicopathological features and a poorer prognosis. Herein, we describe a unique case of a 66-year-old female with a remote history of appendectomy who presented to the emergency room complaining of severe abdominal pain and vomiting. On imaging, the patient was found to have a large inflammatory mass associated with small bowel loops, and the pathology confirmed a mesenteric GIST. The tumor was resected, and the genomic test results confirmed the KIT (exon 11) mutation. Although the tumor had a low mitotic rate, the tumor was large enough to warrant the initiation of adjuvant imatinib mesylate for 36 months with regular bloodwork and imaging.