Nakajo-Nishimura syndrome (NNS) is an extremely rarely reported immunoproteasome-associated autoinflammatory disorder caused by a homozygous mutation of the PSMB8 gene, which encodes immunoproteasome subunit β5i. It was originally described in Japan, and most reported cases are from the Kansai region. There is a 2:1 male-to-female predominance. Consanguinity or familial history is observed in about 70% of the affected families.

NNS usually begins to manifest around age 2 years, but onset may be as early as age 2 months or later, around age 6-12 years. The typical features include a pernio-like eruption that occurs in winter, erythematous nodules, elongated clubbed fingers, and lipodystrophy that predominantly affects the face and upper extremities. Periodic fever is also frequent, and joint contractures may develop as the disease progresses. Hepatosplenomegaly, basal ganglia calcifications, and anemia are prevalent phenomena, and developmental disabilities can occur in some cases.