Langerhans cell sarcoma in the central nervous system mimicking a meningioma: case report and literature review.

Langerhans cell sarcoma (LCS) and Langerhans cell histiocytosis (LCH) are proliferative conditions involving cells that exhibit Langerhans cell features. While LCH can have a variable behavior ranging from benign hyperplasia to a fatal multisystemic disease, LCS represents a rare, aggressive, high-grade malignancy. Central Nervous System (CNS) involvement is rare, and extra-axial lesions can frequently mimic meningiomas or carcinomatous infiltrates, posing a significant diagnostic challenge. We report the case of a 31-year-old male who presented with severe holocranial headache, projectile vomiting, and focal neurological deficits. Brain magnetic resonance imaging revealed a right supratentorial extra-axial mass, initially misdiagnosed as a meningioma. Histopathological examination demonstrated a proliferation of cells with high mitotic activity and conspicuous atypia. Immunohistochemistry showed positivity for S100, CD68, CD1a, and Langerin. Crucially, ultrastructural analysis by electron microscopy revealed the pathognomonic presence of Birbeck granules, confirming the diagnosis of LCS. This case highlights an exceptional presentation of CNS LCS mimicking a meningioma radiologically. It underscores the absolute necessity of integrating clinical, immunohistochemical, and ultrastructural findings to accurately differentiate high-grade histiocytic proliferations from other dural-based non-meningothelial lesions.