J Korean Med Sci 2009; 24: 337-41 ISSN 1011-8934 DOI: 10.3346/jkms.2009.24.2.337 Copyright The Korean Academy of Medical Sciences Granular Cell Tumor of the Descending Colon Treated by Endoscopic Mucosal Resection: A Case Report and Review of the Literature Although colorectal granular cell tumors (GCTs) are rare, their incidental finding has increased as the use of diagnostic colonoscopy has become more common. Here we describe the case of a 41-yr-old man with a GCT in the descending colon that was detected after a screening colonoscopy. Endoscopic examination revealed a yellowish submucosal tumor, 13×12 mm in diameter, in the descending colon. Endoscopic mucosal resection (EMR) followed by histological examination revealed that the tumor was composed of plump histiocyte-like cells with an abundant gran- ular eosinophilic cytoplasm and small round nuclei. The tumor cells expressed S- 100 protein and stained with periodic acid-Schiff, but were negative for desmin and cytokeratin. The resected tumor was diagnosed as a GCT. Colonoscopists should consider the possibility of GCT in the differential diagnosis of yellowish submucos- al tumors of the colon. In such patients, EMR seems to be a feasible and safe ap- proach for diagnosis and treatment. Key Words : Colon; Neoplasms; Endoscopic Mucosal Resection; Granular Cell Tumor; Submucosal Tumor Jae Myung Cha, Joung Il Lee, Kwang Ro Joo, Jae Won Choe, Sung Won Jung, Hyun Phil Shin, and Sung Jik Lim* Departments of Internal Medicine and Pathology*, Kyunghee University College of Medicine, Seoul, Korea Received : 28 October 2007 Accepted : 29 January 2008 Address for correspondence Jae Myung Cha, M.D. Department of Internal Medicine, East-West Neo Medical Center, Kyunghee University College of Medicine, 149 Sangil-dong, Gangdong-gu, Seoul 134-727, Korea Tel : +82.2-440-6113, Fax : +82.2-440-6295 E-mail : dramc@hanmail.net INTRODUCTION Granular cell tumors (GCTs) are relatively rare and thought to be both clinically and histologically benign. Although it may arise virtually anywhere in the gastrointestinal tract, the occurrence of GCTs in the colon is uncommon (1, 2). Instead, these tumors tend to be found incidentally during colono- scopic examinations performed for other reasons, as they are frequently asymptomatic. Endoscopically, a GCT usually appears as a small submucosal nodule, measuring less than 2 cm in diameter (2-5). In the present report, we describe a rare case involving a 41-yr-old man diagnosed with a GCT arising in the descending colon. The tumor was resected by endoscopic mucosal resection (EMR) for histological confir- mation and treatment. In addition, we carefully reviewed the English literature for reports of other cases of colorectal GCT. CASE REPORT A 41-yr-old man underwent colonoscopic examination as part of a routine medical checkup. He had been healthy with- out specific complaints and had no past medical history. He appeared well, and physical examinations showed no abnor- 337 malities. The laboratory findings were all within normal lim- its. At the time of colonoscopy, however, two small polyps were detected in the sigmoid colon and rectum. These were polypectomized using a snare, with the biopsy findings show- ing two adenomas. In the descending colon, a yellowish poly- poid lesion, 13×12 mm in diameter and consisting of a firm nodule covered by intact mucosa, was found (Fig. 1). A sub- mucosal tumor, such as a carcinoid tumor, was suspected and the lesion was resected by EMR for histological confirmation and treatment. After injection of 4 mL of 3% hypertonic saline solution with epinephrine into the submucosa around the lesion for lifting, the tumor was cut electrically with a high-frequency snare. The patient was observed for 30 min and then discharged. No immediate or delayed complica- tions occurred. Histological examination of the resected specimen revealed a submucosal tumor composed of plump histiocyte-like cells with an abundant granular eosinophilic cytoplasm positive for acidophilic periodic acid-Schiff (PAS) staining (Fig. 2). Immunohistochemical analysis showed that the tumor cells expressed S-100 protein (Fig. 3) but were negative for desmin and cytokeratin. The resected tumor was diagnosed as a GCT of the descending colon. During 7 months follow-up, he has been well without dis- ease recurrence.