Abstract
A 57-year-old woman was admitted because of abdominal pain. The Computed Tomography (CT) showed a lobulated mass in the left lower abdomen, which was 15×9×14 cm in diameter. Comparison with the result of the CT at the previous hospital demonstrated that the mass had enlarged rapidly. We diagnosed it as a malignant tumor of the mesenterium or retroperitoneum and conducted left hemicolectomy with en bloc resection of the tumor with no apparent metastasis or peritoneal metastasis. Immunohistochemistry showed leiomyosarcoma because α-SMA and vimentin were positive, but KIT, CD34, S-100 proteins and desmin were negative. This leiomyosarcoma indicated 20 to 30 mitoses/10 high-power fields (HPF) and 56% of Ki-67 labeling index with an extremely high proliferation potential. The patient was discharged from this hospital 23 days after surgery, but died of peritoneal metastasis after three and a half months.
