The<unk>  mechanism of iMCD has not been fully described. It is known that interleukin-6 (IL-6), a molecule that stimulates immune cells, plays a role in some cases of iMCD. IL-6 levels measured in some patients with iMCD increase and decrease with corresponding changes in<unk>  activity, mice treated with IL-6 develop features of iMCD, and blockade of the IL-6 pathway using the medications siltuximab and tocilizumab effectively treats some patients with iMCD. However, many patients with iMCD do not demonstrate elevated levels of IL-6 and IL-6 levels are not strongly correlated with response to treatment with anti-IL-6 medications. In cases where IL-6 does play a role, the underlying cause of elevated IL-6 levels and the cells responsible for producing IL-6 remain unknown. Several theoretical mechanisms for iMCD have been proposed based on existing research and observed similarities between iMCD and other<unk> s that present with similar clinical findings and lymph node histology: * Autoimmune – The immune system may produce antibodies that target healthy cells in the body instead of bacteria and viruses. Self-directed antibodies are commonly seen in autoimmune<unk> s such as systemic lupus erythematous and rheumatoid arthritis. * Autoinflammatory – A mutation in a gene controlling inflammatory systems may contribute to harmful activation of inflammatory pathways in patients with iMCD. * Neoplastic – Genetic mutations that develop in mature cells (somatic mutations) may cause an overgrowth of abnormal cells as in cancers such as lymphoma. * Pathogen – Human herpesvirus 8 (HHV-8) is the known causative agent in HHV-8-associated MCD, which has very similar symptoms and findings to iMCD. While iMCD by definition is not caused by HHV-8, an unknown virus may cause the<unk> . There have been no reported cases of UCD transforming into iMCD.
Idiopathic multicentric Castleman disease
Unicentric Castleman disease
Chronic multifocal Langerhans cell histiocytosis
Follicular lymphoma
Fibrin-associated diffuse large B-cell lymphoma
HHV-8-associated MCD
AIDS-related lymphoma
Progressive nodular histiocytoma