Case Review: PDF OnlyAdult Langerhans Cell Histiocytosis Presenting as Sclerosing Cholangitis in a Liver Explant Case Report and Review of LiteratureShenoy, Krithika MD; Byrnes, Kathleen MD Author Information From the Department of Pathology and Immunology, Washington University in St Louis School of Medicine, St Louis, MO. Reprints: Kathleen Byrnes, MD, Department of Pathology and Immunology, Washington University in St Louis School of Medicine, St Louis, MO 63110. E-mail: [email protected]. The authors have no funding or conflicts to declare. AJSP: Reviews & Reports: January 18, 2022 - Volume - Issue - doi: 10.1097/PCR.0000000000000477 Buy PAP Metrics Abstract Langerhans cell histiocytosis (LCH) is a clonal neoplasm characterized by aberrant proliferation of S100, CD1a, and langerin-positive Langerhans cells. Langerhans cell histiocytosis most commonly presents in the lung as a solitary pulmonary eosinophilic granuloma, but can be disseminated involving the skin and central nervous system. Hepatic involvement by LCH in adults is extremely rare and considered at high risk for mortality. The early stage is easily recognizable with sinusoidal involvement by Langerhans cells. However, the later manifestation of sclerosing cholangitis predominantly affects the perihilar bile ducts and has patchy involvement of the distal bile ducts. This histologically can overlap with primary sclerosing cholangitis and creates a diagnostic dilemma in adults. Sclerosing cholangitis associated with LCH requires liver transplantation for definitive cure. We present the case of a 48-year-old man who had a biopsy with findings of sclerosing cholangitis but no definitive involvement by LCH. He underwent an orthotopic liver transplant showing obliteration of the perihilar bile ducts by Langerhans cells and associated histologic features of sclerosing cholangitis, 16 years after an initial diagnosis of pulmonary LCH. © 2022 Lippincott Williams & Wilkins, Inc.