Rosai-Dorfman disease manifesting as intracranial and intraorbital lesion.

Rosai-Dorfman disease is a rare benign idiopathic histioproliferative disorder usually manifesting as massive painless adenopathy. Extranodal involvement of the Central Nervous System (CNS) mimicking a skull base meningioma is rare. A 42-year-old male presented with painless, progressive left visual loss of 4 months duration. Clinically, he had a left ptosis, proptosis and ophthalmoplegia. Magnetic Resonance Imaging (MRI) of the brain with gadolinium revealed a destructive lesion of the left orbital apex, middle cranial fossa and cavernous sinus. He was treated with corticosteroids and underwent debulking. Pathology showed inflammatory infiltrate in the absence of an infectious agent, emperipolesis and a positive S100 stain was consistent with Rosai-Dorfman disease. As there was no improvement following steroids and debulking, he underwent radiation therapy with significant improvement of his symptoms. Although a rare entity, Rosai-Dorfman disease should be considered in the differential of a skull base lesion.