People who are HIV-positive are more likely to have both Castleman disease and Kaposi's sarcoma.

CNN: Castleman disease

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

CNN: 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.

CNN: Castleman disease

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.

CNN: Castleman disease

It's not clear what causes Castleman disease.

CNN: Castleman disease