It's not clear what causes Castleman disease. Infection by a virus called the human herpesvirus 8 (HHV-8) is associated with Castleman disease, and doctors suspect that it may play a role, especially in multicentric Castleman disease. This virus has also been linked to the development of Kaposi's sarcoma, a cancerous tumor of the blood vessel walls, which is also common in people with multicentric Castleman disease. People who are HIV-positive are more likely to have both Castleman disease and Kaposi's sarcoma.

Researchers aren't clear what the precise role of HHV-8 may be, though it appears that it may 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 and leads to many of the signs and symptoms of Castleman disease.

Generally, people with unicentric Castleman disease aren't infected with HHV-8.

Sep. 03, 2011

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