Aseptic meningitis with relapsing polychondritis mimicking bacterial meningitis.

Relapsing polychondritis (RP) is a rare multisystem autoimmune disease. Though meningitis in RP is not common, some cases with cerebrospinal fluid (CSF) pleocytosis of the lymphocyte cells have been reported. Of the 18 previously reported cases, two cases demonstrated pleocytosis of polymorphonuclear leukocytes (PMN) in the CSF. In addition, cases with a decreased glucose level in the CSF were also seen. Our case also demonstrated pleocytosis of PMN in CSF mimicking bacterial meningitis. In the clinical field, as it is not possible to obtain a culture of CSF on admission day, the glucose level and cellular fraction are considered important. Therefore, meningitis in RP should be considered as a differential diagnosis of bacterial meningitis.