Clinicopathological features of hepatic Langerhans cell histiocytosis: report of ten cases and review of the literature.

The aim was to evaluate the clinical and histopathological characteristics of hepatic Langerhans cell histiocytosis (LCH). Data from 10 patients with hepatic LCH were collected. The clinicopathological features and immunophenotypes of hepatic LCH were assessed. The study included 6 males and 4 females (median age: 20.5 years). Clinical manifestations and imaging findings were non-specific. Six cases had multisystem involvement, while 4 had isolated hepatic LCH. All lesions were located in the portal area. Histologically, Langerhans cells (LCs) with characteristic nuclear grooves infiltrated the bile duct epithelium. Although one case initially presented as sclerosing cholangitis (SC) without detectable LCs, the patient's history of cutaneous LCH provided a crucial diagnostic clue, and Langerhans cell (LC) foci were later confirmed in the explanted liver. Immunohistochemically, these tumor cells were positive for CD1a, S100, and CD207. BRAF V600E mutations were detected in 30 % (3/10) of cases. Five cases displayed unique morphological patterns: 2 exhibited sclerosing cholangitis, 1 resembled inflammatory myofibroblastic tumor (IMT) or EBV-positive inflammatory follicular dendritic cell sarcoma (EBV+ IFDCS), and 2 showed chronic suppurative cholangitis with abscess formation. Hepatic LCH exhibits diverse morphological features. Bile duct epithelial injury with eosinophil infiltration and a history of extrahepatic LCH are important diagnostic clues. Hematoxylin-eosin staining combined with immunohistochemistry (CD1a, S100, CD207) is essential for definitive diagnosis. LCH should be differentiated from hepatic parasitic infections, primary SC, EBV+ IFDCS, and IMT.