Erdheim-Chester disease (ECD) is a rare non-Langerhans'cell histiocytosisdescribed in 1930 by Jakob Erdheim and William Chester, it can present as a multisystemic entity that forms xanthogranulomas which are foamy histiocytes surrounded by fibrotic tissue. Lesions are commonly located in long bones, central nervous system (CNS), cardiovascular system, lungs, kidneys and skin. The CNS is involved in approximately 50% of cases and can compromise both extra or intra-axial structures and therefore can mimic schwannomas or meningiomas, amongst other mass lesions [2, 9]. Clinical presentation will differ from patient to patient thus diagnosis depends greatly in imaging, immunohistochemistry and genetic findings within the pathology analysis [4]. The pathogenesis of this disease remains unknown. It is most commonly found in the middle-aged male population [1, 8]. Here, we present a case of a middle-aged woman with an extra-axial lesion that was initially considered to be neurosarcoidosis proving the diagnostic challenge this entity implies.

Erdheim-Chester disease (ECD) is a rare non-Langerhans'cell histiocytosisdescribed in 1930 by Jakob Erdheim and William Chester, it can present as a multisystemic entity that forms xanthogranulomas which are foamy histiocytes surrounded by brotic tissue. Lesions are commonly located in long bones, central nervous system (CNS), cardiovascular system, lungs, kidneys and skin. The CNS is involved in approximately 50% of cases and can compromise both extra or intra-axial structures and therefore can mimic schwannomas or meningiomas, amongst other mass lesions [2,9]. Clinical presentation will differ from patient to patient thus diagnosis depends greatly in imaging, immunohistochemistry and genetic ndings within the pathology analysis [4]. The pathogenesis of this disease remains unknown. It is most commonly found in the middle-aged male population [1, 8]. Here, we present a case of a middle-aged woman with an extra-axial lesion that was initially considered to be neurosarcoidosis proving the diagnostic challenge this entity implies. Case PresentationA 54-year-old female with a past medical history of systemic arterial hypertension, presented with hemicrania occipital oppressive headache, associated with numbness in both arms and legs, and progressive gait instability. Her initial evaluation was elsewhere and included magnetic resonance imagining (MRI) that reported a mass lesion in the inferior clival region surrounding the right vertebral artery. Embolization of the right vertebral artery was performed, and the patient was referred to the out-