IgG4-related Disease in the Stomach which Was Confused with Gastrointestinal Stromal Tumor (GIST): Two Case Reports and Review of the Literature.

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibro-inflammatory disorder characterized by specific pathological findings and elevated serum IgG4 level. IgG4-RD in the stomach is rare, and occasionally diagnosed as gastric subepithelial tumor (SET) by endoscopy or computed tomography scan. Two female patients in the age group of 40-50 years were diagnosed with 4 cm sized gastric SET. One underwent laparoscopic gastric wedge resection. Another one had a history of subtotal gastrectomy for early gastric cancer and idiopathic thrombocytopenic purpura with oral steroids administration. She underwent a completion total gastrectomy with splenectomy for the gastric SET and ITP. The pathology showed storiform fibrosis, and IgG4 was positive in immunohistochemistry (IHC) stain. IgG4-RD is known as a medical disease that could be treated with oral steroids. The difficulty in preoperative diagnosis of the disease occasionally causes unnecessary gastric resection. Thus, preoperative diagnostic methods for IgG4-RD such as deep biopsy with IHC stain or magnetic resonance imaging are needed.