Relapsing polychondritis-associated limbic encephalitis preceding the emergence of systemic inflammation

A 67-year-old man presented with limbic encephalitis diagnosed from clinical symptoms and abnormal findings on brain magnetic resonance imaging. No abnormalities in laboratory measures of systemic inflammation were observed on admission. Fluorodeoxyglucose-positron emission tomography/computed tomography showed mild uptake in the right auricle. Histological examination of biopsy specimens showed abnormalities consistent with relapsing polychondritis. Subsequently, the patient developed bilateral auricular erythema, an elevated erythrocyte sedimentation rate and a raised serum C-reactive protein level. The early diagnosis of relapsing polychondritis in the present case was clinically challenging, as limbic encephalitis preceded the development of elevated systemic inflammation parameters and typical symptoms of relapsing polychondritis. Fluorodeoxyglucose-positron emission tomography/computed tomography has utility in the systemic evaluation of limbic encephalitis when the underlying cause is unknown.