A 67-year-old Japanese man was admitted to the hospital because of dysphagia. He had a past medical history of hypertension, atrial fibrillation, diabetes mellitus, and ureterolithiasis. Nine months earlier, endoscopy had revealed a protruding lesion in the lower esophagus. A barium study showed a giant elevated lesion with a deep ulcer associated with marked stenosis in the lower esophagus. Endoscopy revealed a multi-nodular protruding tumor covered with smooth and reddish mucosa. CT revealed a low-density mass. Biopsy specimens taken from the lesion showed proliferation of spindle cells, and immunohistochemical analysis of the tumor showed positive staining for c-kit and CD34. A diagnosis of gastrointestinal stromal tumor (GIST) was made and esophagectomy was performed. The resected specimen measured 9.3×8.1×5.1 cm in size and the risk of GIST was estimated to be high by histopathological examination. The diagnosis of submucosal tumor (SMT) should be carefully considered in cases where endoscopy reveals a smooth protruding lesion in the esophagus or compression of the esophagus. Rapidly growing esophageal GISTs should be borne in mind in such cases, and endoscopic follow-up of SMTs measuring more than 2 cm in diameter at least twice a year is thought to be necessary.
