Gastric Duplication Cyst With Occult GIST Component.

A 37-year-old man underwent screening examinations, and a pale-colored submucosal tumor was detected on gastric cardia. Endosonography showed a 15-mm cyst with hypoechoic nodules in the muscularis propria, and endoscopic ultrasound-guided fine-needle aspiration obtained mucinous fluid with atypical spindle cells positive for c-kit, indicating a gastrointestinal stromal tumor. Surgical resection was recommended, but he initially agreed to surveillance. After becoming larger for 8 years, partial gastrectomy was performed for the 22 × 22 × 15-mm capsulized lesion. Surprisingly, its histology was gastric duplication cyst without gastrointestinal stromal tumor. Gastric duplication cyst is a rare entity with the possibility of malignant complications, but careful assessment of endoscopic ultrasound-guided fine-needle aspiration might also be required.