Central nervous system langerhans cell histiocytosis

Abstract

Langerhans cell histiocytosis (LCH) can affect virtually any organ of the human body, including the central nervous system (CNS). Based on correlation of clinical, imaging, and pathology findings, two patterns of CNS-LCH have been identified: granulomatous ("tumorous”) and non-granulomatous "neurodegenerative” (ND)-CNS-LCH. Granulomatous CNS-LCH can manifest with polyuria and polydipsia, seizures, increased intracranial pressure, or other signs, depending on location. The typical location on MRI is extra-axial (hypothalamic-pituitary region, meninges, pineal gland, choroid plexus), and pathology in a proliferative phase reveals CD1a/langerin+ histiocytes. ND-CNS-LCH manifests insidiously with cerebellar and bulbar symptoms. MRI typically reveals parenchymal signal alterations in the cerebellum, pons, basal ganglia, and supratentorial white matter consistent with neuronal loss and demyelination. Biopsies of such lesions are rare. In the few published cases biopsied, variable pathologies are described with perivascular inflammatory changes, variable neuronal loss, demyelination, and gliosis, but are nondiagnostic for CD1a+/CD207+ LCH cells. Granulomatous LCH can be responsive to chemotherapy agents such as vinblastine, cytarabine, or cladribine, while the optimal treatment of ND-CNS-LCH is yet to be defined.