Granular cell tumor occurring in the sigmoid colon treated by endoscopic mucosal resection using a transparent cap...

A case of granular cell tumor occurring in the sigmoid colon is reported. The patient, a 56-year-old man, visited our hospital for further evaluation of occult blood in his stool. Endoscopic examination revealed a yellowish, hemispheric submucosal tumor (SMT) with redness, about 6 mm in diameter, in the sigmoid colon. Endoscopic mucosal resection using a transparent cap (EMR-C) was performed, and histological examination revealed that the tumor consisted of a nested growth of large tumor cells with ample granular cytoplasm and small round nuclei. The tumor cells expressed S-100 protein and were stained with neuron-specific enolase (NSE) and periodic acid-Schiff, but were negative for desmin, vimentin, and cytokeratin. The resected tumor was diagnosed as a granular cell tumor. This may be the first report of a colorectal granular cell tumor successfully treated with EMR-C.