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Granular cell tumors (GCTs) are generally thought to be of Schwann cell origin and are typically S-100 positive. Up to 11% of these tumors affect the gastrointestinal tract, most commonly the esophagus, colon, and stomach. While GCTs are mostly benign, malignant and metastatic GCTs have been reported. GCTs are usually found incidentally during esophagogastroduodenoscopy, colonoscopy, imaging studies or during the evaluation of non-specific symptoms. Endoscopically, they are typically yellow in appearance with intact mucosa. On endoscopic ultrasound, they usually are hypoechoic, homogenous, smooth-edged lesions that appear to originate from the submucosal layer, although other endoscopic and ultrasound appearances have been described. There is no consensus on how to treat GCT. Surgical and conservative approaches have been described in the literature. GCTs can also affect the biliary tract, where patients may be misdiagnosed with cholangiocarcinoma. We explore the epidemiology, histology, clinical presentation, diagnosis and treatment of these tumors in the gastrointestinal tract, including the pharynx, esophagus, stomach, small intestine, large intestine and the perianal region. In addition, GCTs in the biliary tract are reviewed.