Nate Eisenhut, DO, Ningxin Zeng, MD; Trios Health, Kennewick, WA
Introduction: Leiomyosarcomas (LMS) involving the colon are exceedingly rare and can be difficult to both detect and diagnose until significant advancement of disease. Early diagnosis and distinguishing LMS from Gastrointestinal Stromal Tumors (GIST) is of utmost importance for treatment strategy. Colonoscopy may not be a sensitive tool for both detection and surveillance of LMS. We present a case of rectosigmoid LMS initially presenting as a fecal ball appearance, however surgical biopsy revealed ultimate diagnosis of LMS.
Methods: 56-year-old female with history of possible peritoneal mass was referred to GI for evaluation of acute on chronic abdominal pain with severe constipation and episodes of hematochezia. Despite two days of bowel preparation a large impacted "fecal ball" was discovered at the rectosigmoid colon junction, which was partially obstructed and prevented passage of even a pediatric colonoscope. Further attempts with water pump and decompression tools revealed pink tissue under the fecal cover and forceps manipulation caused bleeding. Several deep biopsies were obtained and pathological report indicated inflammatory exudate with focal stromal atypia. CT abdomen revealed intussusception with noted possible mass effect. Surgical resection revealed large necrotic and ulcerated appearing mass confirmed to be LMS by immunohistochemical analysis which revealed strong response to both desmin and smooth muscle actin (SMA) with significant mitotic features as expected with LMS while also demonstrating negative CD34, CD117 (c-Kit), and S100 characteristics. Discussion: Colonic primary LMS are rare with few cases reported, furthermore the endoscopic appearance of LMS is not well described in the literature. Two previously reported cases of colonic LMS had nearly normal colonoscopy findings. This patient also had colonoscopies previously in 2013 and 2017 significant only for small sessile serrated adenomas. Therefore routine colonoscopy may not be a sufficient tool to detect or provide adequate surveillance for rare cancers like LMS, given the fast growth and need for biopsy of deep submucosal tissue to reveal highly pleomorphic atypical cells. In this case we present LMS that appeared to be a fecal impaction upon initial endoscopic evaluation. Deep biopsy may help lead to initial diagnosis before surgical approach, however more research needs to be conducted to improve our understanding of both detection and treatment of LMS.
LMS presenting as fecal ball
Leiomyosarcoma proliferation in colonic submucosa (H&E stain)
Disclosures: Nate Eisenhut indicated no relevant financial relationships. Ningxin Zeng indicated no relevant financial relationships.