Castleman disease: application of modern classification in a Canadian center.

BACKGROUND: CD (Castleman disease) is a rare and heterogeneous condition that poses a diagnostic and management challenge. Classification of CD has changed dramatically in recent years. This study aims to describe our experience with diagnosis and treatment of CD at a center in Canada. RESEARCH DESIGN AND METHODS: We conducted a retrospective study of our cohort of CD patients evaluated and treated at the University of British Columbia between 2016-2025. RESULTS: A total of 23 patients with biopsy-confirmed CD were included. 7/23 had unicentric CD (UCD), 1/23 had Oligocentric CD (OligoCD), and 15/23 had multicentric CD (MCD). All MCD cases were idiopathic (iMCD) and of these, 3/15 had iMCD-TAFRO (thrombocytopenia, anasarca, fever, reticulin myelofibrosis or renal dysfunction, and organomegaly), 4/15 had iMCD-idiopathic plasmacytic lymphadenopathy (iMCD-IPL), and 8/15 had iMCD-not otherwise specified (iMCD-NOS). Median time to diagnosis was shortest for iMCD-TAFRO (1 month) and longest in iMCD-IPL (82 months). 100% of iMCD-TAFRO, 100% of iMCD-IPL, and 86% of iMCD-NOS cases treated with Siltuximab or Tocilizumab had at least a partial response. CONCLUSIONS: This study demonstrates the heterogeneous presentation, natural history, and response to treatment of CD in a North American center, and highlights the importance of awareness of the different subtypes of CD. Key limitations are its retrospective design and small sample size.