It's not clear what causes Castleman disease. However, infection by a virus called human herpesvirus 8 (HHV-8) is associated with multicentric Castleman disease.

The HHV-8 virus has also been linked to the development of Kaposi's sarcoma, a cancerous tumor of the blood vessel walls that can be a complication of HIV/AIDS. Studies have found that HHV-8 is present in HIV-positive people who have Castleman disease, and in 40 to 50 percent of HIV-negative people with Castleman disease.

The precise role of HHV-8 is unclear. But it appears to cause malfunctioning immune system cells to reproduce rapidly. The immune system cells produce a protein called interleukin-6 (IL-6) that contributes to the overgrowth of lymphatic cells.

Aug. 27, 2014

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