[Relapsing polychondritis presenting as encephalitis].

Relapsing polychondritis (RP) is a rare, generalized autoimmune disorder that is characterized by recurrent inflammation of various cartilaginous structures. Involvement of the central nervous system is rarely observed in RP. Here we report a case of encephalitis associated with RP. A 60-year-old man presented with headache and bilateral ear swelling. Three weeks later, he came to our hospital because of the acute onset of a speech impediment. A non-contrast computed tomography scan of the head showed slight high-density areas in his left frontal lobe, but he refused to be admitted and went home. On the next day, he developed acalculia, agraphia, right-left disorientation, and mild right hemiparesis. Brain MRI revealed hyperintensity areas in the left frontal sulcus on fluid-attenuated inversion recovery (FLAIR) images, and these hyperintensity areas were enhanced by gadolinium. Therefore, the patient's symptoms were diagnosed as focal epilepsy caused by meningoencephalitis. Other examinations, including laboratory blood tests, cerebrospinal fluid tests, and a cerebral angiography, were all negative. Therefore, a brain biopsy of the left frontal cortex was performed 5 days after the patient's admission. Pathological findings revealed chronic inflammation of the meninges, so prednisone was administered. After receiving oral prednisone, the patient's bilateral ear swelling dramatically improved and the lesions apparent on cranial MRI gradually subsided. The patient was diagnosed with RP by a neurologist after discharge from the hospital. In this study, early diagnosis and steroid treatment is recommended for patients with neurological complications due to RP.