When your immune system forgets how to turn off

Health · Published 20 October 2026 Swipe more like this →

In short: Normally, your immune system acts like a security team that leaves once the threat is neutralized. In Castleman disease, the alarm stays on. This constant state of high alert causes your lymph nodes to overgrow, creating a persistent cycle of inflammation that can damage your body's organs.

Castleman disease is a rare immune dysregulation disorder characterized by an overgrowth of cells in the lymph nodes. While healthy immune systems settle down after fighting germs, this condition keeps the system constantly defending the body. This leads to systemic inflammation and physical changes in the lymph node tissue, such as the formation of concentric rings with prominent vascularity.

The disease is categorized into two primary forms based on its reach. Unicentric Castleman disease (UCD) is localized, affecting a single lymph node or a single region. It accounts for about 75% to 80% of cases and often presents with no symptoms at all. In contrast, Multicentric Castleman disease (MCD) is more widespread, affecting multiple regions of the body and typically presenting with flu-like symptoms such as fever, night sweats, and weight loss.

MCD is further subdivided into three distinct types based on underlying causes. The first is associated with the POEMS syndrome, a rare blood disorder that can damage nerves. The second is linked to human herpesvirus-8 (HHV-8) and is more common in immunocompromised individuals. The third is idiopathic (iMCD), meaning its cause is currently unknown. Research has identified Interleukin-6 (IL-6) as a key driver of the inflammatory response in these cases, leading to the development of targeted monoclonal antibodies for treatment.

Diagnosis is complex because symptoms often overlap with infections or autoimmune disorders. Doctors use a combination of blood and urine tests to check for inflammation and anemia, imaging like CT or PET scans to locate enlarged nodes or an enlarged spleen, and ultimately a lymph node biopsy. This biopsy is essential to distinguish Castleman disease from other conditions like lymphoma.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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