Recurrent Chemical Meningitis Due to Parasellar Epidermoid Cyst.

Intracranial epidermoid cysts are exceedingly rare lesions that result from a disorder of gastrulation. They are seen only in the pediatric patient population. We describe a 44-year-old Hispanic woman who presented with acute confusion. The family reported two months of progressive headaches and two weeks of fever, blurred central vision, and restricted visual fields. On examination, the patient appeared ill, with a low-grade fever and stiff neck. Neurological testing was limited but grossly non-focal. Computerized tomography (CT) of the head and magnetic resonance imaging (MRI) of the brain showed a large cystic mass arising in the sella, where it displaced the normal pituitary gland. Cerebrospinal fluid (CSF) showed mildly elevated opening pressure with high protein, low glucose, and neutrophilic pleocytosis. Extensive serum and CSF evaluation were negative for infectious agents. The patient was initially started on empiric treatment for presumed infectious meningoencephalitis. As tests for bacterial and viral pathogens were normal, she was switched to fluconazole. The mental status returned to normal and she was discharged home with close follow up. She returned one month later with a recurrent headache, nausea, and stiff neck. The examination showed meningismus but was otherwise non-focal. MRI of the brain showed no change in the parasellar mass. Repeat CSF showed an even higher white blood cell (WBC) count and protein with continued hypo-glycorrhachia. She underwent trans-nasal trans-sphenoidal hypophysectomy and pathology revealed a squamous epithelium-lined keratin-filled cyst suggestive of an epidermoid cyst. The patient responded well to surgery and was discharged on pituitary hormone supplements alone. To our knowledge, this is a first adult case of recurrent chemical meningitis secondary to a ruptured epidermoid cyst in the sella.