MRI findings of CNS sarcoidosis

Sarcoidosis is a multisystemic disease of unknown origin characterized path ologically by the presence of noncaseating epithelioid granulomas. Symptoma tic involvement of the CNS may develop in a patient with known sarcoidosis or ii may be the initial manifestation. Intracranial sarcoidosis may includ e meningeal disease, cranial neuropathy, hypothalamic and pituitary dysfunc tion and both intraaxial and extraaxial mass. The MRI features are variable and non specific, so differentiation from other lesions (multiple sclerosi s, tumour, meningitis, vasculitis) may be difficult, especially in the abse nce of extracranial disease. Patients with symptoms usually have correspond ing CNS lesions at MR imaging, except for cranial nerves involvement. Under therapy, resolution of lesions at MR imaging lags behind resolution of cli nical symptoms. MRI may contribute to confirm a clinically suspected diagno sis or detect subclinical involvement. MRI is also very helpful for follow- up under therapy.