Adenocarcinoma Arising From a Gastric Duplication Cyst With Lymph Node Metastasis.

Gastric duplication cysts (GDCs) are a relatively rare congenital anomalies and are mostly diagnosed in the early years of life. Herein, we report a very rare surgical case of adenocarcinoma arising from a GDC with lymph node metastasis. A 78-year-old woman was referred to our hospital because of elevated serum levels of cancer antigen (CA) 19-9. Endoscopic ultrasound, contrast fistulography, and computed tomography showed a cystic lesion communicating with the lesser curvature of the stomach. The serum levels of CA 19-9 were high, and fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) imaging demonstrated a slightly enlarged lymph node with high FDG uptake after four months. The size of the cyst was unchanged. It was diagnosed as a GDC. The enlarged lymph node was highly likely to be malignant. Hence, we performed a distal gastrectomy involving the origin of entry and whole body of the GDC with en bloc regional lymphadenectomy. The postoperative pathology was consistent with GDC with moderately differentiated adenocarcinoma and lymph node metastasis. Adjuvant chemotherapy with tegafur-gimeracil-oteracil potassium (S-1) was administered for 12 months. At present, the patient is alive, with no recurrence of the lesion even four years after the operation. GDCs in adults are rare and may predispose to malignancy. Early diagnosis and prompt surgical intervention are important for favorable outcomes.