Langerhans Cell Histiocytosis in the central nervous system, cranial and spinal bones: imaging features

INTRODUCTION: Langerhans Cell Histiocytosis (LCH) is a rare neoplastic disorder characterized by monoclonal proliferation and tissue infiltration by pathological dendritic cells, often associated with abnormal activation of the MAPK signaling pathway and BRAF V600E mutation. The diagnosis is established through clinical, radiological, and histopathological evaluation. It can manifest in various organs, notably bones, skin, and the hypothalamic-pituitary axis. The assessment of central nervous system (CNS) involvement in LCH includes both parenchymal and non-parenchymal structures, including craniofacial bones, hypothalamic-pituitary axis, and meninges. AREAS COVERED: We used the PubMed database and reviewed relevant English-language literature published from 1989 to 2024. The sources included original researches, reviews and case reports, excluding editorials and letters to the editor. This review focuses on the existing evidence regarding the imaging, clinical, and pathological aspects of CNS, cranial and spinal bones involvement in LCH and its differential diagnosis. EXPERT OPINION: Imaging plays an essential role in properly diagnosing, guiding biopsy and monitoring treatment. Computed tomography (CT) is particularly helpful for evaluating bone involvement, while magnetic resonance imaging (MRI) is preferred for assessing parenchymal brain and meningeal lesions. The disease can present in either tumoral or neurodegenerative forms, manifesting with varied symptoms depending on the affected region.