Idiopathic multicentric Castleman disease
A rare lymphoproliferative disorder of unknown cause.
Idiopathic multicentric Castleman disease (iMCD) is a subtype of Castleman disease, a group of lymphoproliferative disorders characterized by lymph node enlargement, characteristic microscopic features, and a range of symptoms. People with iMCD have enlarged lymph nodes in multiple regions and often experience flu-like symptoms, abnormal blood test findings, and dysfunction of vital organs such as the liver, kidneys, and bone marrow. The cause of iMCD is unknown, and it has features often found in autoimmune diseases and cancers.
Quick Facts
- Specialty
- Hematology, immunology, rheumatology, pathology
- Diagnosis
- Based on patient history, physical exam, laboratory testing, medical imaging, histopathology
- Frequency
- approximately 1500-1800 new cases per year in the United States
Facts from the source article.
Lore & Background
Idiopathic multicentric Castleman disease (iMCD) was first described as part of Castleman disease by Dr. Benjamin Castleman in 1956. It is distinguished from other subtypes by the presence of enlarged lymph nodes in multiple regions and the absence of human herpesvirus 8 (HHV-8) infection. The disease mechanism is not fully understood, but interleukin-6 (IL-6) plays a role in some cases, with levels rising and falling alongside disease activity. However, many patients do not have elevated IL-6, and response to anti-IL-6 medications is not strongly correlated with IL-6 levels.
Reader's Guide
iMCD is significant as a distinct disorder within the Castleman disease spectrum, requiring careful diagnosis to differentiate it from unicentric Castleman disease and HHV-8-associated MCD. Diagnosis relies on evidence-based consensus criteria including patient history, physical exam, laboratory testing, radiologic imaging, and lymph node biopsy. The disease can present with severe symptoms such as TAFRO syndrome (thrombocytopenia, anasarca, myelofibrosis, renal dysfunction, organomegaly), which was first described in Japanese patients in 2010 but has since been reported globally. Treatment may involve immunosuppressants and chemotherapy, and the Castleman Disease Collaborative Network is the largest organization focused on research, awareness, and patient support. The cause remains unknown, with proposed mechanisms including autoimmune, autoinflammatory, neoplastic, and pathogen-driven theories, though no genetic variant has been validated as disease-causing.
Did You Know?
- iMCD is not caused by uncontrolled HHV-8 infection, unlike HHV-8-associated MCD.
- Interleukin-6 (IL-6) levels in some iMCD patients increase and decrease with disease activity.
- TAFRO syndrome is a distinct clinical subtype of iMCD first described in Japanese patients in 2010.
- No cases of unicentric Castleman disease transforming into iMCD have been reported.
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