SMALL INTESTINE GASTROINTESTINAL STROMAL TUMOR MASQUERADING AS UTERINE MALIGNANCY

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INTRODUCTION

Gastrointestinal stromal tumors (GISTs) constitute <1% of gastrointestinal tumors, with extra-gastrointestinal stromal tumors (EGIST) comprising <10% of all GISTs. We present the rare case of a 68-year-old female, with a preoperatively mistaken uterine carcinoma, diagnosed as a primary EGIST located in the posterior cul-de-sac connected to the jejunum.

CASE DESCRIPTION

A 68-year-old female underwent an elective Roux-en-Y gastric bypass. Over the following months, postoperative complications included peritonitis, anastomotic leak, septic shock, liver abscesses, intractable nausea and vomiting. Incidentally, computed tomographic imaging identified a mass in the uterus. Magnetic resonance imaging demonstrated a right hemipelvis mass thought to originate from the right adnexa. Cervical biopsy, pap smear and tumor panels were unremarkable. The patient was scheduled for total abdominal hysterectomy (TAH) and intraoperatively, a 15 cm mass was found to be connected to the jejunum, in the posterior cul-de-sac. Small bowel resection with biopsies was performed in lieu of the planned TAH. Biopsies stained positive for CD117, DOG-I, and SMA consistent with GIST. The patient was then started on imatinib and eventually discharged in stable condition.

DISCUSSION

Although rare, GISTs are the most common mesenchymal neoplasm of the GI tract and have a near-universal expression of the CD117 antigen. They originate from the interstitial cells of Cajal and typically present as a subepithelial, intraluminal mass. Tumors are most commonly identified in the stomach (40-60%) followed by the jejunum and ileum (25-30%). EGISTs are rare, and if found, are usually associated with metastases from an undetected intra-gastrointestinal tumor. According to a recent report, <30 cases of GISTs were preoperatively mistaken for gynecological neoplasms. Our case is a unique addition to the existing literature. A combination of surgical resection and adjuvant chemotherapy is recommended in treatment of GISTs. Imatinib remains one of the mainstay therapies for most GISTs. EGISTs are a rare and aggressive group of stromal tumors and should be included in the differential diagnosis of a patient presenting with an extra-luminal abdominal mass. Imaging fails to identify presumed gynecological neoplasms as GISTs. It is prudent to consider non-gynecological tumors for pelvic masses.