Schwannoma of the stomach with elevated preoperative serum carbohydrate antigen 19-9: report of a case

We herein report a case of a gastric schwannoma with elevated preoperative serum carbohydrate antigen 19-9 (CA19-9) (155.2 U/ml, normal range 0–36.9 U/ml). A 59-year-old Japanese man was admitted to our hospital for treatment of a submucosal tumor of the stomach detected by barium meal, upper gastrointestinal endoscopy, and computed tomography. Endoscopic examination revealed a 3-cm diameter submucosal tumor in the antrum of the stomach, but biopsy of the lesion was unable to confirm the diagnosis. Positron emission tomography to evaluate the malignant potential showed a high uptake of ¹⁸F-fluorodeoxyglucose in the tumor. Laparoscopy-assisted distal gastrectomy was therefore performed. The histopathological findings of the surgical specimen revealed a benign gastric schwannoma, positive for S-100 protein. The postoperative serum CA19-9 levels gradually decreased and normalized. To the best of our knowledge, this is the first report of a gastric schwannoma with elevated serum CA19-9.