Longitudinal, natural history study reveals the disease burden of idiopathic multicentric Castleman disease.

Idiopathic multicentric Castleman disease (iMCD) is a rare hematologic disorder with heterogeneous presentations ranging from moderate constitutional symptoms to life-threatening multiorgan system involvement. iMCD patients present with vastly different clinical subtypes, with some patients demonstrating thrombocytopenia, anasarca, fever/elevated C-reactive protein, reticulin fibrosis/renal failure, and organomegaly (TAFRO) and others demonstrating more mild/moderate symptoms with potential for severe disease (not otherwise specified, NOS). Due to its rarity and heterogeneity, the natural history and long-term burden of iMCD are poorly understood. We investigated real-world medical data from ACCELERATE, a large natural history registry of Castleman disease patients, to better characterize the long-term disease burden experienced by these patients. We found that iMCD-TAFRO patients face significant hospitalization burden, requiring more time in the hospital than iMCD-NOS patients during the year surrounding diagnosis (median [IQR] 36 [18, 61] days vs. 0 [0, 4] days; p.