[Recent advances in diagnosis and treatment of idiopathic multicentric Castleman disease].

Multicentric Castleman disease (MCD) is a rare polyclonal lymphoproliferative disease that causes systemic inflammation. In Western countries, human herpesvirus 8 (HHV-8) is frequently associated with MCD pathogenesis, especially in human immunodeficiency virus (HIV)-positive cases, whereas HHV-8 is seldom related to MCD cases in Japan and is referred to as idiopathic MCD (iMCD). iMCD can present as a variety of systemic symptoms and characteristic laboratory abnormalities due to IL-6 overproduction, occasionally causing organ failure. Although there have been no recent studies other than pathologic studies of iMCD, its association with TAFRO (thrombocytopenia, anasarca, reticulin fibrosis of the bone marrow, renal dysfunction, and organomegaly) syndrome has recently attracted attention in Japan as well as internationally. In 2015, a research team for iMCD published a medical reference guide and organized regional core hospitals in Japan for the diagnosis and treatment of iMCD. As a result, iMCD was designated the 331st intractable disease by the Japanese Ministry of Health, Labor and Welfare. iMCD can be expected to have a good prognosis if properly diagnosed and treated. We are optimistic that iMCD research will aid the development of medical treatment for this disease.