A rare presentation of IgG4 related disease as a gastric antral lesion: Case report and review of the literature

•IgG4RD is a newly recognized systemic disease affecting nearly every organ.•IgG4RD presenting as a gastric mass is extremely rare.•Preoperative biopsy is mandatory for definitive diagnosis.•When diagnosed before surgery, the treatment is medical with IV steroids. Immunoglobulin G4 related disease is a recently recognized systemic fibro-inflammatory disorder affecting virtually every organ in the body, characterized by lympho-plasmacytic dense infiltrates rich in IgG4 positive plasmacytes along with storiform fibrosis, inconstantly associated with elevated serum IgG4 levels. Few cases of Immunoglobulin G4 related disease occurring solely in the stomach have been published. We herein present a rare case of a 57 year old male patient presenting with an incidentally discovered asymptomatic pre-pyloric submucosal gastric lesion confused with a gastro-intestinal stromal tumor with failed endoscopic biopsy attempts due to tumor mobility. The patient underwent wedge resection of the lesion which was diagnosed postoperatively as Immunoglobulin G4 related disease. Immunoglobulin G4 related disease presenting as a solitary lesion in the stomach is a very rare condition. It should be kept in the differential diagnosis of a submucosal mass or polyp. The treatment is medical with systemic steroid therapy. Obtaining a tissue biopsy is of extreme importance to avoid unnecessary surgery.