A 50-Year-Old Man with an Uncommon Polyp

Abstract

Purpose: A 50-year-old asymptomatic man came for repeat colonoscopy. One year before, he underwent a screening colonoscopy during which a diminutive polyp was found in the cecum. The polyp was removed with moderate difficulty. The biopsy showed a mucosal fragment with focal erosion. His gastroenterologist recommended repeat colonoscopy in 1 year. During repeat endoscopy, a 4 mm yellowish sessile hard polyp was found in the cecum. The Jumbo forceps could not excise the polyp, so polypectomy with a hot snare was performed successfully. There were no complications. Histological examination revealed a completely excised granular cell tumor. Methods: Granular cell tumor (GCT) is a relatively rare soft tissue neoplastic tumor of neural derivation, which commonly occurs in the oral cavity and subcutaneous tissue and is uncommon in the colon and rectum. The GI tract harbors approximately 5% of all GCTs. The most common site for GCT in the GI tract is the esophagus, followed by the duodenum, anus and stomach. Lesions can be incidental findings, or they may give rise to obstructive or pressure symptoms when large enough and in a critical location. Malignancy is rare and has been found to correlate with tumor size (more than 60% of metastatic GCTs were larger than 4 cm). Since colonic GCTs are usually benign, endoscopic removal is the most appropriate therapy. Results: Diagnosis is based on histopathological findings: (1) small, uniform nuclei without mitotic figures; (2) histiocyte-like bland-looking neoplastic cells with abundant granular eosinophilic cytoplasm containing acidophilic, PAS-positive, diastase-resistant granules; (3) stain positively for S-100 protein, neuron-specific enolase, and NK1-C3 in almost all cases. The tumor cells are non-immunoreactive for epithelial, muscle, endothelial and glial cell markers. This is useful for differentiating a granular cell tumor from other diagnostic possibilities. The found lesion had the typical characteristics of GCT. Since the patient was asymptomatic we did not pursue further work-up. He will have a repeat colonoscopy in 1 year. Conclusion: In conclusion, GCTs of the colon can be found incidentally during colonoscopy and endoscopic removal of the tumor is a safe and feasible treatment. Endoscopists should consider GCTs in the differential diagnosis of submucosal tumors of the colon.