Diagnostic and therapy of an early-stage primary leiomyosarcoma of the sigmoid colon: A case report.

Key Clinical Message: Primary leiomyosarcoma of the colon is a very rare tumor entity. Because of unspecific findings, diagnostic can be challenging. Most cases are diagnosed in advanced stages with poor overall survival. Unclear histological findings of smooth muscle cell tissue in colon biopsies together with a tumor of the colon wall in computed tomography (CT) imaging should lead to the differential diagnosis of primary colonic leiomyosarcoma and further diagnostic procedures. Abstract: Primary colonic leiomyosarcoma is an extremely rare tumor entity arising from smooth muscle cells in the colon wall. Only 0.1% of all colorectal malignancies are leiomyosarcomas. Most patients are diagnosed in advanced disease stages. The overall survival rates are low, and recurrence rates are high. Only few data regarding the outcome in localized early disease stages are available. We report the case of an early-stage primary leiomyosarcoma of the sigmoid colon treated with surgical resection. We present the case of a 53-year-old male patient who underwent a colonoscopy due to intermittent rectal bleeding. Colonoscopy revealed an intraluminal polypoid growing tumor in the sigmoid colon. A biopsy was performed with inconclusive histological results. A CT scan revealed a process in the sigmoid colon with wall thickening; there was no evidence of metastatic lesions. After laparoscopic oncological resection of the sigmoid colon, histological examination surprisingly revealed a localized high-grade leiomyosarcoma. Primary leiomyosarcoma of the colon is a rare tumor entity and diagnostic can be challenging. Only a few patients with colonic leiomyosarcoma diagnosed in localized early disease stages and treated with complete surgical resection have been reported in the literature. These patients seem to have a better prognosis with longer overall survival. Because of unspecific diagnostic findings and the lack of symptoms in early disease stages, interdisciplinary collaborations between gastroenterologists, radiologists, pathologists, and surgeons are crucial for early diagnosis and treatment.