Teaching Neuroimages: Rare skull base involvement in neurosarcoidosis

A 57-year-old woman was admitted with a tonic-clonic seizure on a background of systemic sarcoidosis with uveitis and hilar lymphadenopathy. She had previously been well and stopped steroids one year before presentation. CT showed a sclerotic lesion with focal lucent areas in the skull base MRI revealed a frontal FLAIR hyperintense oedematous lesion with meningeal enhancement in gadolinium T1 This appearance on imaging evokes broad differential diagnoses such as sarcoidosis, fungal (although she had increasing lesion size despite six-month treatment with amphotericin B), craniofacial fibrous dysplasia, atypical lymphoma, nasopharyngeal carcinoma, myeloma and tuberculosis, therefore necessitating biopsy for definitive evaluation. Transsphenoidal biopsy revealed non-caseating granulomatous inflammation and the patient was started on oral glucocorticoid therapy for sarcoidosis Neurosarcoidosis with skull base bone involvement is uncommonly reported ^1,2.