LAUSR

IgG4-related disease (IgG4-RD) is an immune-mediated disorder in which abundant IgG4-positive plasma cells infiltrate the affected organs. IgG4-RD presenting as a submucosal tumor of the stomach is rare, and preoperative diagnosis is difficult. Herein, we demonstrate endoscopic full-thickness resection (EFTR) of IgG4RD presenting as a submucosal stomach tumor for the first time. Our patient (a 77-year-old man) had a 20-mm submucosal tumor in the posterior wall of the stomach, which was initially identified by upper gastrointestinal endoscopy (▶Fig. 1). Endoscopic ultrasonography showed a low-echoic mass derived from the muscularis propria of the stomach (▶Fig. 2). Fine-needle aspiration biopsy could not confirm the diagnosis. Enhanced computed tomography showed neither lymph node enlargement nor metastasis. A malignant gastrointestinal stromal tumor (GIST) was suspected and EFTR was performed with the patient under general anesthesia. The mucosa was incised around the submucosal tumor using a FlushKnife BT 2.5 (Fujifilm, Tokyo, Japan). After the lesion had been pulled towards the stomach lumen using two clips and a thread, the resection was completed using an IT-Knife 2 (Olympus, Tokyo, Japan). Fibrosis made this lesion unusually difficult to resect; therefore, two clips were required for sufficient traction. The perforation site was closed using SureClips (Micro-Tech, Nanjing, China) and a detachable snare (Olympus) (▶Fig. 3; ▶Video 1). Histopathology showed a mass with lymphoplasmacytic infiltration, fibrosis, and IgG4-positive plasma cells (▶Fig. 4). A postoperative elevation of serum IgG4 levels was noted. No recurrence was observed within 1 year. This case was one of definite IgG4-RD presenting as a gastric submucosal tumor. EFTR allowed accurate diagnosis. IgG4RD may present as a gastric lesion and often cannot be differentiated preoperatively from a GIST [1]. Patients with such lesions have undergone various types of surgery [2]; however, this is the first reE-Videos