Mixed Multiple Autoimmune Syndrome Type 3 With Coexistence of Primary Biliary Cholangitis, Inflammatory Myopathy, and Chronic Thyroiditis: A Case Report

Multiple autoimmune syndromes (MAS) are a heterogeneous group of endocrine and non-endocrine autoimmune diseases. We present the case of a 78-year-old female with mixed type 3 MAS due to the presence of primary biliary cholangitis (PBC) and idiopathic inflammatory myopathy (IIM) with hypothyroidism due to Hashimoto's disease (HD), who was treated with corticosteroid pulses and azathioprine. Mixed MAS cases are rare, which implies the need for further studies to establish protocols for subclinical screening and management of simultaneous autoimmune pathologies with varying degrees of severity.