Abstract
RATIONALE: Membranous nephropathy (MN) is an important and common cause of nephrotic syndrome in adults. Overlap syndrome is an infrequent clinical subgroup characterized by the coexistence of autoimmune hepatitis, primary biliary cholangitis or primary sclerosing cholangitis. Coexistence of MN and autoimmune liver diseases is rare. Several reports have documented the concurrent presence of multiple autoimmune diseases, suggesting a potential mechanism linking these disorders. PATIENTS CONCERNS: A 53-year-old male patient diagnosed with phospholipase A2 receptor-related MN accompanied by recurrent increases in aminotransferases during treatment. DIAGNOSES: The patient was finally diagnosed as MN with primary biliary cholangitis-autoimmune hepatitis overlap syndrome based on histopathological findings. INTERVENTIONS: A combination of rituximab, oral methylprednisolone, and ursodeoxycholic acid. OUTCOMES: The patient achieved complete immunological remission and partial remission of proteinuria. LESSONS: We encountered a unique case with autoimmune disease of both liver and kidney. Treatment plans should be tailored to each patient's specific condition since there is no standard protocol. The pathological mechanisms of overlapping autoimmune diseases require further understanding.