Erdheim-Chester with central nervous system involvement: Complex histopathological diagnosis and neurosurgical challenges in a rare histiocytic disorder.

Background: Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis classified as a neoplastic hematopoietic disorder. It typically affects adults aged 40-56 years, with a male predominance (2.3-3:1). ECD presents with a wide clinical spectrum, ranging from asymptomatic bone lesions (90% of cases) to severe multisystem involvement, including cardiovascular, pulmonary, and central nervous systems (CNSs). CNS involvement occurs in approximately 50% of cases and is associated with increased morbidity and mortality. The BRAF V600E mutation is found in a significant subset of patients and plays a critical role in diagnosis and targeted therapy. Case Description: We present the case of a 39-year-old male with central hypothyroidism, progressive visual impairment, and headaches. Magnetic resonance imaging revealed two extra-axial supratentorial lesions. Surgical resection was performed using a "one-and-a-half " frontotemporal craniotomy, providing optimal multi-angled access. Histopathological examination confirmed ECD with a BRAF V600E mutation. The patient had an uneventful postoperative recovery. Conclusion: This case highlights the strategic utility of the "one-and-a-half " frontotemporal craniotomy in the resection of complex supratentorial lesions. It also underscores the critical importance of molecular diagnostics, particularly the identification of the BRAF V600E mutation, in guiding treatment decisions in ECD.