Submucosal colonic fecalith mimicking a submucosal malignant tumor at the anastomotic site after colon cancer: A case report.

Submucosal fecaliths occurring at the anastomotic site after intestinal surgery are rare. In addition, endoscopic histological diagnosis of submucosal lesions is challenging. The present study describes a rare case of a submucosal lesion suspected of being a submucosal tumor at the anastomotic site following colectomy, resulting in a postoperative diagnosis of submucosal fecalith. A 70-year-old man had a history of abdominal surgery, including colectomy for colon cancer and small bowel resection for gastrointestinal stromal tumor (GIST). During follow-up, a calcified submucosal lesion was detected near the anastomotic site after transverse colectomy, and its size gradually increased. Colonic GIST was suspected based on diagnostic modalities. The patient underwent partial laparoscopic resection of the small intestine and transverse colon, including the previous anastomotic site. Macroscopically and microscopically, the resected specimen was not identified as a neoplasm, but was instead revealed to be a cystic lesion containing soft and brownish materials, which was not connected to the colonic lumen, suggesting bowel duplication containing a fecalith. In conclusion, the present study reports on the case of intestinal duplication containing a submucosal fecalith mimicking submucosal neoplasm.