Castleman Disease: The Great Mimicker

Castleman disease is a rare illness where your immune system acts up. It causes the filtering stations in your body, called lymph nodes, to get too big and overwork. These overgrown nodes release too many „distress signals“ (proteins like Interleukin-6, or IL-6). This sends your entire body into an inflammatory overdrive.

While the overgrown lymph nodes are generally not cancerous, the body-wide inflammation they cause can be very serious.

The Two Types of Castleman Disease

The disease comes in two main forms, and they are treated very differently:

1. Unicentric Castleman Disease (UCD)

• What it is: The problem is limited to a single enlarged lymph node or group of nodes in just one part of the body.
• Symptoms: Often, patients feel fine and only find a lump or have issues because the enlarged node is pressing on something, like causing a cough.
• Treatment: The cure is usually surgery to remove the single affected node.

2. Multicentric Castleman Disease (MCD)

• What it is: This is the more serious, body-wide form. It involves lymph nodes in many different areas and causes severe, systemic „flu-like“ symptoms.
• The Cause: MCD is often separated into two groups: one linked to the HHV-8 virus (common in people with HIV) and another called Idiopathic MCD (iMCD), where the cause is unknown.
• Treatment: Surgery won’t work. Patients need medication that targets the overactive immune system, like drugs that block the harmful IL-6 protein.

How Doctors Confirm Castleman Disease

If a doctor suspects CD, they will need to do a few things to rule out all other diseases:

1. Tissue Sample (Biopsy): This is the most important step. A surgeon removes an entire swollen lymph node. This tissue is sent to a lab where a specialist looks for the unique signs of Castleman disease under a microscope.
2. Blood Tests: These check for signs of inflammation, anemia, and whether you have the HHV-8 virus or HIV.
3. Imaging (Scans): CT or PET scans help doctors see where the enlarged lymph nodes are and how many areas are affected.

Getting the right diagnosis fast is critical, especially for the serious MCD type, because quick treatment can prevent severe organ damage.

Why Is It So Hard to Get a Diagnosis?

Doctors call Castleman disease the „great mimicker“ because its symptoms look like many other common, and even serious, illnesses—like the flu, autoimmune disorders (such as Lupus), or a type of cancer called lymphoma.

Because there’s no single, simple blood test for it, getting a diagnosis can take a long time, sometimes months or years. This is called a diagnostic odyssey.

If you have these symptoms, talk to your doctor about whether CD could be a possibility:

• Systemic Symptoms: Fevers that keep coming back, drenching night sweats, and feeling absolutely exhausted (fatigue).
• Swollen Glands: Enlarged lymph nodes in more than one spot (neck, armpit, groin) that don’t go away.
• Other Swelling: Unexpected weight loss, and swelling or fluid buildup (like in your legs or belly).

Trusted Places for More Information

The information in this article about Castleman’s Disease is for educational and informational purposes only. It is intended to help you understand your symptoms and inform your conversations with a medical professional. This content is not a substitute for professional medical advice, diagnosis, or treatment.

Due to the serious nature of Castleman Disease and its overlap with other conditions, never delay seeking professional medical attention based on something you read online. If you suspect you or a loved one may have this condition, please consult a qualified physician immediately.

If you are pursuing a diagnosis, it’s best to connect with doctors and patient groups who focus on rare diseases.

• Castleman Disease Collaborative Network (CDCN): A patient-led global organization focused on research and connecting patients with specialists.
• National Organization for Rare Disorders (NORD): A resource for all rare diseases.

References

1. Fajgenbaum, D. C., & Shanti, R. (2020). Overview of Castleman disease. Blood, American Society of Hematology 135(16), 1353-1360.
2. Castleman Disease Collaborative Network (CDCN). 
3. Mayo Clinic. (2023). Castleman disease: Symptoms and causes. 
4. Van Rhee, F. G., et al. (2020). International evidence-based consensus diagnostic and treatment guidelines for unicentric Castleman disease. Blood Advances, 4(22), 5753-5764.