Aseptic leptomeningitis induced by azathioprine in systemic lupus erythematosus: a rare manifestation.

Systemic lupus erythematosus (SLE) is an autoimmune systemic disease and these patients can have neurological involvement; however, aseptic leptomeningitis is considered to be a very rare feature, observed in 1.4-2.0% of patients. Here, we described a case of a young male with SLE treated with azathioprine with progressive headache, which revealed diffuse posterior fossa leptomeningitis, relatively sparing the supratentorial compartment, that represent an adverse drug reaction - a rare manifestation of central nervous system involvement in SLE. Treatment with azathioprine was interrupted and methylprednisolone was initiated and the patient has significant improvement of his neurological state in 5 days later, demonstrating total involution of the leptomeningeal enhancement on MRI follow-up.