Ileal Gastrointestinal Stromal Tumor Presenting With Subacute Intestinal Obstruction and Synchronous Peritoneal Metastases: A Case Report.

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasms of the gastrointestinal tract. They most often arise in the stomach, followed by the small intestine. Small bowel GISTs usually present with gastrointestinal bleeding, anemia, abdominal pain, or nonspecific symptoms, whereas intestinal obstruction is uncommon because these tumors typically grow outward from the bowel wall. We report the case of a 58-year-old woman with no previous abdominal surgery who presented with one month of abdominal pain, constipation, and vomiting, which progressed to complete absence of stool and flatus for 48 hours. CT and MRI showed a 4.5-cm exophytic distal ileal mass with multiple peritoneal nodules and no liver lesions or lymphadenopathy. Because of the obstructive presentation, exploratory laparoscopy was performed. Intraoperative findings showed a stenosing ileal tumor and diffuse peritoneal implants. Frozen-section analysis of two nodules suggested metastatic GIST, and segmental ileal resection with primary anastomosis was performed to relieve the obstruction and establish a definitive diagnosis. Histology showed a spindle-cell GIST positive for KIT (CD117) and DOG1, with a mitotic rate of 4/50 high-power fields. The peritoneal nodules were metastatic implants. The postoperative course was uneventful, and imatinib 400 mg daily was started one week later. After nearly two years of clinical and radiological follow-up, the patient remained stable without disease progression. This report highlights that ileal GIST should be considered in cases of unexplained small bowel obstruction, especially when imaging shows an exophytic mass without lymphadenopathy.