Spontaneous rupture of a sigmoid colon gastrointestinal stromal tumor manifesting as pneumoretroperitoneum with localized peritonitis: report of a case.

Colonic gastrointestinal stromal tumors (GISTs) account for only 5%-10% of tumors arising in the digestive tract. Spontaneous rupture is a very rare manifestation of a GIST; however, we report what to our knowledge is the first documented case of pneumoretroperitoneum caused by the rupture of a GIST. A 77-year-old woman was admitted to our hospital with acute abdominal pain and hematochezia. Colonoscopy showed luminal narrowing in the sigmoid colon, but no definite mucosal defect. Computed tomography (CT) showed an air-containing heterogeneous mass, 9.7 × 9.3 cm, in the pelvic cavity and a small amount of air in the retroperitoneum. Emergency laparotomy revealed a ruptured sigmoid colonic GIST with localized peritonitis. Pathologic examination confirmed that the tumor was composed mainly of round epithelioid cells. It was immunohistochemically positive for CD34 and negative for C-kit protein. This report describes how we successfully managed pneumoretroperitoneum with localized peritonitis caused by the spontaneous rupture of an epithelioid GIST originating from the sigmoid colon.