[Gastric cancer concurrent with IgG4-related disease: A clinical case and a review of literature].

The paper presents the data available in the literature on IgG4-related disease (IgG4-RD) concurrent with malignancies at different sites, as well as possible common pathogenetic mechanisms of their development and morphological diagnostic criteria for IgG4-RD. The authors give their own observation of gastric signet ring cell carcinoma concurrent with morphologically verified IgG4-RD.