[Cryopyrin-associated periodic fever syndrome (CAPS) presenting as early-onset dementia, lacking typical recurrent fever or skin rash: a case report].

A 54-year-old man with a university degree was admitted to our hospital because of a two-year history of progressive dementia. He had familial sensorineural hearing loss and had been treated for epilepsy since his 30s. On admission, he showed severe dementia and parkinsonism without fever or skin rash. Systemic inflammation was evident, and the CSF cell count and IL-6 level were elevated to 53/μl and 307 ‍pg/ml, respectively. Brain MRI demonstrated diffuse brain atrophy. More detailed anamnesis revealed a history of rheumatoid arthritis in childhood and aseptic meningitis in his 20s. Genetic examination for autoinflammatory diseases demonstrated compound heterozygotic mutations in the NLRP3 gene, causing cryopyrin-associated periodic fever syndrome (CAPS). This case was atypical CAPS presenting as early-onset progressive dementia, without recurrent fever or urticaria-like eruption which are usually seen in this disease.