Case Report: IgG4-RD-related autoimmune pancreatitis combined with monoclonal gammopathy of undetermined significance

Jinhu Wei¹Xiang Chen¹Li Chen¹Yao Xie¹Wanman Li¹Jiyuan Liang^2*

• ¹Liuzhou Liutie Central Hospital, Liuzhou, China
• ²The Second Affiliated Hospital of Guangxi University of Science and Technology, Liuzhou, China

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated chronic fibrotic inflammatory disorder. The coexistence of IgG4-RD with monoclonal gammopathy of undetermined significance (MGUS) is relatively rare, with only a few cases reported in the literature.The coexistence of this disease with an unexplained monoclonal gammopathy of undetermined significance (MGUS) is relatively rare in clinical practice, and only a few cases have been reported so far. This article reports a case of a 79-year-old male patient with clinical manifestations of persistent upper abdominal pain of unknown cause and recurrent pleural effusion. Auxiliary examinations indicated positive serum antinuclear antibodies and persistently positive IgG4; three-dimensional imaging reconstruction showed mild pancreatic swelling and the peripancreatic fat planes appeared blurredblurred fat interstitial space around the pancreas, which was consistent with the manifestations of pancreatitis. According to the "International Consensus Diagnostic Criteria for Autoimmune Pancreatitis (AIP)"of the diagnostic criteria of the International Pancreatic Disease AssociationAccording to the standards of the "Chinese Guidelines for the Diagnosis and Treatment of Autoimmune Pancreatitis (Shanghai, 2023)", the patient was diagnosed with IgG4-RD AIP(1). At the same time, the patient's serum protein electrophoresis M protein was 2.34 g/L, and immunofixation electrophoresis confirmed it to be IgG-λ-type M protein. Combined with bone marrow smear and biopsy results, it was diagnosed as having MGUS. To our knowledge, this represents a rare case of IgG4-RD AIP concomitant with MGUS, and we provide an in-depth discussion of its clinical management and potential pathogenic association. this case is the first reported case of a patient with AIP combined with MGUS in the literature.