2019 Volume 57 Issue 2 Pages 186-194
A 75-year-old woman had undergone colonoscopy because of a positive fecal immunochemical test for occult blood. She had no symptoms, but the colonoscopy revealed a 3-cm protruding tumor in the ascending colon; biopsy demonstrated atypical spindle-shaped cells. Computed tomography revealed a solid tumor with good enhancement. There was no lymph node swelling around the tumor and no distant metastasis. She underwent right hemicolectomy. Histopathology revealed nodular proliferation of spindle-shaped cells with mitotic activity and vascular invasion. Immunohistochemistry demonstrated a positive reaction for desmin and HHF35 and a negative reaction for c-kit and CD34; the tumor was diagnosed as leiomyosarcoma. Leiomyosarcoma of the colon is a rare disease presenting as a characteristically large tumor, with clinical symptoms such as hematochezia and abdominal fullness. This case is extremely unusual because the patient was asymptomatic and the diagnosis was made by a fecal occult blood test during a routine health examination.
