Chest x-ray revealing a Castleman disease tumor.

Castleman Disease: When a Tumor Isn't Just a Tumor

Theo Raines in Health & Wellness December 2025 • 4 min read.

"Uncover the diagnostic challenge of Castleman disease and its critical distinction from other mediastinal tumors."

Mediastinal tumors, or growths in the chest area between your lungs, are often discovered by chance during routine check-ups or scans for something else. While many are benign, figuring out exactly what they are can be tricky for doctors. Benign mediastinal lesions pose a significant diagnostic challenge to radiologists and pathologists.

These growths often have patterns that hint at certain conditions, but certainty can be elusive. When doctors can't be sure, surgeons may need to perform a biopsy during surgery to get a diagnosis and decide on the best course of action. This is where understanding rare conditions like Castleman disease becomes critical.

This article explores a case of Castleman disease, highlighting why it should always be considered when evaluating mediastinal tumors. By understanding this condition, we can improve diagnostic accuracy and patient care.

What is Castleman Disease?

Chest x-ray revealing a Castleman disease tumor.

Castleman's disease (CD) is a rare condition where the lymph nodes, part of your immune system, become enlarged. It's not cancer, but rather a type of lymphoproliferative disorder, meaning it involves an abnormal increase in the number of lymphocytes, a type of white blood cell.

CD can be either unicentric, affecting a single lymph node or region, or multicentric, affecting multiple lymph nodes throughout the body. The most common form, known as the hyaline vascular variant, usually appears as a single mass in the chest (mediastinum).

Unicentric Castleman Disease (UCD): Affects a single lymph node or region. Often asymptomatic and treatable with surgery.
Multicentric Castleman Disease (MCD): Affects multiple lymph nodes throughout the body. Can cause systemic symptoms like fever, weight loss, and fatigue. May be associated with other conditions like HIV or HHV-8 infection.
Hyaline Vascular Variant: The most common type, characterized by distinctive changes in the lymph node structure, including prominent blood vessels.

Diagnosing Castleman disease requires a combination of imaging studies and a biopsy of the affected lymph node. This helps distinguish it from other conditions with similar symptoms, such as lymphomas and other types of tumors. Once diagnosed, treatment options vary depending on the type and severity of the disease.

The Importance of Awareness

Castleman disease, though rare, represents a critical consideration in the differential diagnosis of mediastinal tumors. By increasing awareness and understanding of this condition, healthcare professionals can improve diagnostic accuracy, leading to better outcomes for patients. If you experience unusual symptoms or have concerns about your health, always consult with a qualified medical professional for personalized advice and treatment.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

What exactly is Castleman disease, and why is it important to recognize it?

Castleman disease (CD) is a rare lymphoproliferative disorder, not a cancer, where lymph nodes become enlarged due to an abnormal increase in lymphocytes. It's important to recognize CD because it can mimic other mediastinal tumors, leading to potential misdiagnosis. CD has subtypes such as unicentric Castleman Disease (UCD), affecting a single lymph node, and multicentric Castleman Disease (MCD), affecting multiple lymph nodes throughout the body. The hyaline vascular variant is the most common type.

What's the difference between Unicentric and Multicentric Castleman Disease, and why does it matter?

Unicentric Castleman Disease (UCD) affects a single lymph node or region and is often asymptomatic, making it treatable with surgery. Multicentric Castleman Disease (MCD) affects multiple lymph nodes and can cause systemic symptoms, such as fever and weight loss, and may be associated with HIV or HHV-8 infection. The distinction is important because the treatment approaches and the implications for overall health are significantly different.

How do doctors diagnose Castleman disease, and why can't they just tell from looking at scans?

Diagnosing Castleman disease (CD) involves a combination of imaging studies and a biopsy of the affected lymph node. The biopsy is critical to distinguish CD from other conditions with similar symptoms, such as lymphomas and other types of tumors. Without these diagnostic steps, CD could easily be mistaken for other mediastinal tumors, leading to inappropriate treatment.

Why is it so important for doctors to be aware of Castleman disease?

Awareness of Castleman disease (CD) is crucial because it represents a critical consideration in the differential diagnosis of mediastinal tumors. Improving awareness among healthcare professionals can improve diagnostic accuracy, leading to better outcomes for patients. It ensures that CD is considered alongside other possibilities, which is key due to its rarity and potential for misdiagnosis.

What is the hyaline vascular variant of Castleman disease, and why is it significant?

The hyaline vascular variant is the most common form of Castleman disease, characterized by distinctive changes in the lymph node structure, including prominent blood vessels. It is important because it often presents as a single mass in the chest (mediastinum), which can be detected during routine scans. Recognizing this variant helps in early diagnosis and appropriate management of Castleman disease.