Castleman disease: Year of the Zebra

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Castleman disease refers to a group of rare immune-related conditions characterized by lymph node enlargement and an overactive immune system, which can result in various systemic symptoms.
While it might sound like a single condition, Castleman disease comes in two main forms, and each behaves very differently.
The first is unicentric Castleman disease or UCD. It's a milder form that affects a single node or several lymph nodes in one specific region, most commonly in the neck, chest, or abdomen.
We still don't know what causes UCD but we do know it stays limited to one area and doesn't trigger the entire immune system.
Many individuals with UCD have no symptoms and find out about their enlarged lymph node by chance during a routine checkup.
When symptoms do appear, they usually come from the swollen lymph node pressing on nearby structures, causing pain or discomfort.
Individuals often report a feeling of chest pressure, difficulty breathing or swallowing. Or a noticeable lump in their neck, armpit, or groin.
The second form is multicentric Castleman disease or MCD, which is more widespread and can lead to life-threatening organ dysfunction.
Here, the immune system goes into overdrive, producing too much of the inflammatory chemical IL-6 and triggering the growth of B cells and plasma cells across multiple lymph nodes.
So instead of just one, many lymph nodes throughout the body become enlarged. This overactive immune response also causes symptoms like fever, tiredness, night sweats, and weight loss.
Some people may also develop a swollen liver and spleen. In severe cases, the body can release a flood of inflammatory chemicals, which may lead to liver and kidney failure.
This can cause fluid backup, leading to leg swelling and fluid in the belly, known as ascites. Based on the factors that drive excess IL-6 production, MCD is classified into three subtypes.
In HHV8 associated MCD, a virus called human herpes virus 8 is the trigger, especially in individuals with a weakened immune system like those living with HIV.
In poems associated MCD, poems stands for polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes.
This type of Castleman disease is triggered by a cancerous growth of plasma cells where abnormal plasma cells produce excessive IL-6, fueling inflammation.
Finally, in idiopathic MCD, sometimes called HHV 8 negative MCD, we don't know what's driving the excess IL-6 production.
Castleman disease can often present similarly to infections, lymphomas, and autoimmune conditions. So the key to diagnosis is a lymph node biopsy.
Imaging tests such as PET and CT scans help determine whether the condition is limited to one area, suggesting UCD or spread across multiple regions pointing to MCD.
Next, blood work can help assess the inflammation. Low C-reactive protein and erythrocyte sedimentation rate suggest UCD while high C-reactive protein and erythrocyte sedimentation rate mean inflammation is raging, suggesting MCD.
Other tests will check for organ dysfunction, such as liver function tests, albumin, and creatinine. Finally, there may be additional tests done to check for HIV and human herpes virus 8 infections.
Treatment of UCD usually involves surgical removal of the enlarged lymph node. However, if surgery is not possible, a medication called rituximab might help shrink the lymph node.
On the flip side, management of MCD depends on the subtype. The first line treatment of HHV8 associated MCD is rituximab, which targets B cells infected with the virus.
Treatment for poems associated MCD focuses on getting rid of abnormal plasma cells, using medicines similar to those used for a type of blood cancer called multiple myeloma.
Finally, idiopathic MCD relies on a monoclonal antibody called ciltuximab, which works by blocking IL-6. In individuals where cetuximab is not effective, rituximab, corticosteroids, or chemotherapy regimens may be used.
Alright, as a quick recap, Castleman disease describes a group of rare immune-related conditions characterized by lymph node enlargement and a range of symptoms caused by an overactive immune system.
The unicentric type affects a single node or several lymph nodes in one specific region and is generally milder, while the multicentric type affects various lymph nodes in the body and can cause life-threatening organ dysfunction.
Diagnosis primarily relies on lymph node biopsy, while treatment depends on the specific type of Castleman disease.
Castleman disease: Video & Causes | Osmosis