Definition:

Castleman disease is a rare lymphoproliferative disorder with two primary subtypes that vary in presentation and course. Unicentric Castleman disease is localized and carries an excellent prognosis. Multicentric Castleman disease can be associated with HIV and human herpesvirus-8 and is characterized by generalized lymphadenopathy and systemic symptoms, such as fever, fatigue, anorexia, anemia, and cachexia. Castleman disease is unique in that dysregulated secretion of interleukin-6 (IL-6) plays a central pathogenetic role, although the exact events precipitating the oversecretion of IL-6 are unknown. Recently, two antibody-based therapeutics targeting components of the IL-6/IL-6R complex have been approved for the treatment of Castleman disease. Tocilizumab is a monoclonal antibody directed against the IL-6 receptor, and siltuximab is a monoclonal antibody specific for IL-6.