Nakajo–Nishimura syndrome (NNS) is an autosomal recessive disease characterized by remittent fever, skin rash, emaciation of the face and upper body, and long gnarled fingers with contractures. Since Nakajo reported the first patients in Japan in 1939, only a few papers describing similar patients have been published. The detailed characteristics of NNS are unknown because it is very rare.
Arima et al. (2011) reported that proteasomal dysfunction due to a mutation of the proteasome subunit beta type 8 gene (PSMB8) encoding immunoproteasome subunit β5i caused various symptoms of NNS. Since then, reports of NNS have increased gradually. Nevertheless, some patients with NNS may be misdiagnosed with collagen–related diseases or inflammatory myopathies because they show similar symptoms to these diseases.
There is no established treatment for NNS, however, the administration of an anti–IL–6 receptor antibody and JAK inhibitor is possibly effective. If patients with NNS are diagnosed and treated early, they can maintain their activities of daily living.