An Association Between Autoimmune Hepatitis (AIH) and Immunoglobulin G4-Related Disease (IgG4-RD) in a Male Diagnosed...

IgG4-associated disorders (IgG4-RD) are disease states that are marked by a fibrotic inflammatory disease process that can affect hepatic tissue, salivary glands, and other organs in the body. The hepatic expression of this condition, termed IgG4-associated autoimmune hepatitis (IgG4-AIH), occurs infrequently and can resemble conventional autoimmune hepatitis (AIH), especially during concurrent manifestation with primary Sjögren's syndrome (pSS), thereby creating diagnostic and therapeutic challenges. We report a clinical case involving a 56-year-old gentleman with an established medical background of type 2 diabetes and hypothyroidism who developed right upper quadrant discomfort, jaundice, and laboratory evidence of cholestasis. Workup revealed hypergammaglobulinemia, positive ANA and anti-Ro antibodies, and markedly elevated serum IgG4 (4.31 g/L). Imaging showed hepatomegaly and bilateral parotid gland enlargement. Liver biopsy showed interface hepatitis, rosette formation, storiform fibrosis, and the dense infiltration of IgG4+ plasma cells (7-10/HPF, IgG4:IgG ratio 50-60%). The patient satisfied diagnostic criteria for both IgG4-AIH and pSS. Treatment with prednisolone, hydroxychloroquine, and azathioprine brought about clinical and biochemical improvement. Rituximab was contemplated for escalated therapy due to the overlapping autoimmune conditions and systemic nature of IgG4-RD. This case highlights the diagnostic difficulty of IgG4-AIH when occurring alongside pSS and illustrates the need for liver biopsy with IgG4 immunostaining in testing atypical hepatitis cases. It is essential to differentiate IgG4-AIH from classic AIH or pSS-related liver disease, as it may have a different treatment response and prognosis. Further studies would assist in refining the diagnostic criteria and therapeutic strategies for overlapping autoimmune syndromes.