S3509 An Uncommon Overlap: Primary Biliary Cholangitis and Autoimmune Hepatitis in a Man With Rosai-Dorfman Disease

Introduction: Primary biliary cholangitis (PBC) and type 1 autoimmune hepatitis (AIH) overlap disease is when both autoimmune conditions occur at the same time resulting in liver disease. Both conditions occur more commonly in women and can be seen with concurrent autoimmune conditions. Rosai-Dorfman disease (RDD) is a rare subtype of non-Langerhans’s histiocytosis, a disorder of histocyte proliferation which typically affects lymph nodes, skin, or sinuses but other organs can be affected. We present a rare cause of PBC/AIH overlap in a man later found to having concurrent RDD. Case Description/Methods: A 57-year-old man was evaluated for 3 years of progressively elevated liver enzymes. He had no medical history, took no medications and physical examination was normal. Total bilirubin was 2.1 mg/dL, alkaline phosphatase 609 U/L, ALT 93 U/L, AST 78 U/L. Laboratory testing showed a positive anti-nuclear antibody, anti-smooth muscle antibody and anti-mitochondrial antibody and immunoglobulin G was 1722 mg/dL. Laboratory testing for other chronic liver diseases was negative. Liver ultrasound and magnetic resonance imaging of the abdomen were normal. Liver biopsy showed marked periportal and lobular lymphoplasmocytic infiltrate and rare aggregates of histiocytes and interface activity and bridging fibrosis were present, consistent with PBC, AIH or PBC/AIH overlap. He started budesonide, azathioprine and ursodiol and liver enzymes improved. Four months later the patient felt an enlarging lower abdominal mass. Ultrasound showed a 1.8 cm ovoid, hypoechoic lesion with internal echogenic material in the subcutaneous fat which was excised. He developed a right gluteal mass and biopsy showed dense fibrous soft tissue and adipose tissue almost completely replaced by clusters of histiocytes and a dense lymphoplasmacytic inflammatory infiltrate. The histiocytic areas showed numerous plasma cells and lymphocytes. He was diagnosed with RDD. As he was asymptomatic and next generations sequencing did not identify any therapy targets, patient is undergoing surveillance with imaging every 3 months. Discussion: PBC/AIH overlap is a rare, autoimmune chronic liver disease, especially in men. RDD is another rare disease with histiocytic proliferation and has been reported to occur in patients with underlying autoimmune disease and the underlying etiology for the link is unknown. Upon review of the literature this is the first care of a patient with active PBC/AIH overlap disease then being diagnosed with RDD.