[Gatrointestinal stromal tumor: a case report]. / Tumor del estroma gastrointestinal: reporte de un caso.

Gastrointestinal stromal tumors are the most common mesenquimal neoplasms of the gastrointestinal tract. A preoperative diagnose of GIST it is very difficult to make, but up to 5% of the cases initially appear as a pelvic mass. Clinical case: 45-year-old patient attended in medical service by unspecific pain in the lower abdomen of several weeks of evolution. The abdominopelvic tomography evidence collection of 9×8 cm above of the uterus and sigma's right with air in the cavity, it is was compatible with pelvic abscess. Due to increased pain, we realized emergency exploratory laparotomy, which showed a 14 cm tumor, dependent of the small intestine, without ascites or involvement other organs of the digestive or reproductive tract. The excision of the tumor was successfully (non intraoperative rupture). The pathological study reported a bowel piece of 20 cm, in which a tumor of 14 cm with large central cavitation was identified. Histologically showed diffuse growth pattern and neoplastic epithelioid cells with low rate of mitosis (mitosis 1-2/5 mm2). The immunohistochemistry test reports strong expression of DOG-1 and focal expression in CD117 (c-kit), with very low proliferation index (Ki67). The molecular pathology study identified a mutation in exon 11, codon 557-558, the c-kit gene in the p.W557_K558del position. We use imatinib (400 mg/24 h) from the second month after surgery. Today keep in treatment, and clinical and laboratories following every month: in addition, to CT scans scheduled every 6 months.