Granular cell tumor of the rectum: a case report and review of the literature

A 47-year-old Japanese woman with a 5-year history of alcoholism was admitt ed to the Ryukyu University Hospital for the treatment of the alcoholism. F or evaluation of observed changes in her bowel habits, she underwent colono scopy, which revealed seven small polyps spread throughout the entire large intestine. Six of the polyps were in the colon; one was an adenoma and fiv e were hyperplastic polyps. The remaining polyp, in the rectum, was an 8-mm submucosal tumor. Pathological analysis of a biopsy of the lesion in the r ectum indicated a possible diagnosis of adenocarcinoma. Endoscopic ultrason ography (EUS) demonstrated a submucosal hypoechoic nodule, involving the mu cosa and the muscularis propria. Subsequently, the patient underwent a radi cal low anterior resection of rectum. The lesion was a submucosal tumor wit h ulceration. The tumor consisted of granular tumor cells which were positi ve for S-100 protein, neuron-specific enolase, and periodic acid schiff (PA S) stain, but negative for desmin and vimentin. Granular cell tumor is rare in the gastrointestinal tract. As a result, such tumors can be misinterpre ted to indicate a possible malignancy on either a biopsy or EUS.