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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Hematology

Orienting Yourself After a Diagnosis

At a Glance

Castleman disease is a rare, non-cancerous lymphatic disorder that causes enlarged lymph nodes and systemic inflammation. It is a highly treatable condition with clear medical guidelines. Treatment depends on whether the disease is Unicentric (one area) or Multicentric (body-wide).

Receiving a diagnosis of Castleman disease can feel overwhelming, especially since you may never have heard of it before. It is often first mentioned in the same breath as cancer or lymphoma, which can cause immediate panic. However, it is important to take a breath and orient yourself: while it shares some characteristics with those conditions, it is biologically distinct and highly treatable [1][2].

What Exactly Is Castleman Disease?

Castleman disease is officially described as a non-clonal lymphoproliferative disorder [3][4]. To understand this in plain language, let’s break it down:

  • Non-clonal: In cancer, a single “rogue” cell makes identical copies (clones) of itself that grow uncontrollably. Castleman disease is “non-clonal,” meaning the cells are not necessarily genetically mutated clones; instead, they are normal immune cells that are growing in an abnormal way [5][6].
  • Lymphoproliferative: This simply means your lymphatic system (the network that helps your body fight germs) is “proliferating,” or growing more cells than it needs [3].

In short: Castleman disease is not a cancer of the cells themselves, but a disorder of how the cells behave and communicate. Think of it like a “false alarm” in your immune system that won’t turn off.

The Role of the “Fire Alarm”: Interleukin-6 (IL-6)

The primary driver behind many symptoms of Castleman disease is a protein called Interleukin-6 (IL-6) [7][8].

  • The Communication Error: IL-6 is like a chemical “fire alarm” your body uses to signal an infection or injury. In Castleman disease, your body produces too much IL-6 even when there is no fire [7][9].
  • The Result: This excess IL-6 causes your lymph nodes to enlarge and can lead to a “flu-like” feeling, including fevers, night sweats, and fatigue [10][11].

Three Reasons for Hope

While the disease is rare—affecting roughly 6,500 to 7,700 newly diagnosed people in the U.S. each year—you are entering a landscape of rapidly advancing care:

  1. It Is Highly Treatable: For many, especially those with the “Unicentric” form, surgery can be curative [12][13]. For others, medications that block IL-6 (like siltuximab) have shown high success in managing the disease long-term [14][15].
  2. Clear Standards of Care Exist: In the past, doctors had to guess. Today, there are international, evidence-based consensus guidelines for diagnosing and treating every subtype of the disease [16][4].
  3. The CDCN is Leading the Way: The Castleman Disease Collaborative Network (CDCN) is a global organization that has revolutionized research for this condition [17]. They have united the world’s top experts to ensure that no patient—and no doctor—has to face this disease alone [18].

Understanding Your Subtype

Your doctors will determine which of the two main types you have, as this determines your treatment path:

  • Unicentric Castleman Disease (UCD): Affects only a single lymph node or one area of lymph nodes [3][19]. UCD is often “silent” and discovered accidentally on a routine scan or by noticing a painless lump.
  • Multicentric Castleman Disease (MCD): Affects multiple lymph node regions throughout the body and often involves systemic (body-wide) symptoms [3][20].

Because this disease is so rare, it is common for local doctors to be unfamiliar with the latest protocols. Do not be afraid to advocate for yourself or seek a specialist who works closely with the current international guidelines [18][4].

Common questions in this guide

Is Castleman disease a type of cancer?
No, Castleman disease is not cancer or lymphoma. It is classified as a non-clonal lymphoproliferative disorder, which means it involves normal immune cells growing and behaving abnormally, rather than mutated cancer cells cloning themselves out of control.
What is the difference between Unicentric and Multicentric Castleman disease?
Unicentric Castleman disease (UCD) affects only a single lymph node or one area of lymph nodes, and is often discovered by accident. Multicentric Castleman disease (MCD) affects multiple lymph node regions throughout the body and typically causes systemic symptoms like fevers and fatigue.
Why does Castleman disease cause flu-like symptoms?
Many symptoms of Castleman disease are driven by an overproduction of Interleukin-6 (IL-6), a protein that signals infection or injury. In Castleman disease, the body produces too much IL-6 even when there is no infection, triggering a false alarm that causes fevers, night sweats, and severe fatigue.
How is Castleman disease treated?
Treatment depends entirely on your specific subtype. Unicentric Castleman disease can often be cured through surgical removal of the affected lymph node. Multicentric Castleman disease is highly treatable using targeted medications, like siltuximab, that block the excess IL-6 protein in your body.
Why do doctors check my IL-6 and CRP levels?
IL-6 and C-reactive protein (CRP) are inflammatory markers in your blood. Doctors measure these levels to gauge the extent of the inflammation caused by Castleman disease and to actively monitor how well your body is responding to treatment.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my biopsy and scans, do I have Unicentric (UCD) or Multicentric (MCD) Castleman disease?
  2. 2.Is my disease 'idiopathic' (iMCD) or is it associated with a virus like HHV-8?
  3. 3.What are my IL-6 and CRP levels, and how will we monitor them during treatment?
  4. 4.How much experience does this facility have in treating Castleman disease specifically, rather than lymphoma?
  5. 5.Is my care being coordinated with experts from the Castleman Disease Collaborative Network (CDCN)?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (20)
  1. 1

    Clinical features and outcomes in patients with human immunodeficiency virus-negative, Castleman's disease: a single medical center study in Tunisia.

    Chabchoub I, Salah RB, Kallel R, et al.

    Romanian journal of internal medicine = Revue roumaine de medecine interne 2024; (62(1)):20-32 doi:10.2478/rjim-2023-0028.

    PMID: 37948573
  2. 2

    Pathology of Castleman Disease.

    Wu D, Lim MS, Jaffe ES

    Hematology/oncology clinics of North America 2018; (32(1)):37-52 doi:10.1016/j.hoc.2017.09.004.

    PMID: 29157618
  3. 3

    Clinical Presentation, Treatment, and Outcomes of 28 Patients With Castleman Disease: A Retrospective Analysis of an Italian Cohort.

    Cristinelli C, Merli M, Lucioni M, et al.

    EJHaem 2025; (6(6)):e70158 doi:10.1002/jha2.70158.

    PMID: 41210897
  4. 4

    Multicentric Castlemans disease. Symptoms, diagnostics and therapy.

    Adam Z, Řehák Z, Adamová Z, et al.

    Vnitrni lekarstvi 2022; (68(1)):41-53.

    PMID: 35459346
  5. 5

    Role of immunohistochemistry in differentiating between reactive and malignant lymphoid hyperplasia - A cross-sectional study.

    Chourasia S, Badkur S, Kumar A, Shah M

    Bioinformation 2025; (21(10)):3470-3474 doi:10.6026/973206300213470.

    PMID: 41623763
  6. 6

    Density and size of lymphoid follicles are useful clues in differentiating primary intestinal follicular lymphoma from intestinal reactive lymphoid hyperplasia.

    Li HN, Wang RC, Chen JP, et al.

    Diagnostic pathology 2020; (15(1)):82 doi:10.1186/s13000-020-00991-3.

    PMID: 32635930
  7. 7

    Snapshot Look at Castleman Disease.

    Jitaru C, Zlampa N, Dima D, et al.

    Journal of cellular and molecular medicine 2026; (30(3)):e70961 doi:10.1111/jcmm.70961.

    PMID: 41664979
  8. 8

    Castleman disease: Case series of two surgical patients from different ends of the disease spectrum with literature review.

    C G RR, B S

    International journal of surgery case reports 2018; (53()):163-167 doi:10.1016/j.ijscr.2018.10.053.

    PMID: 30399511
  9. 9

    A Rare Lymphoproliferative Disease: Castleman Disease

    Gündüz E, Özdemir N, Bakanay ŞM, Karakuş S

    Turkish journal of haematology : official journal of Turkish Society of Haematology 2021; (38(4)):314-320 doi:10.4274/tjh.galenos.2021.2021.0440.

    PMID: 34719151
  10. 10

    The Role of Interleukin-6 in Castleman Disease.

    Yoshizaki K, Murayama S, Ito H, Koga T

    Hematology/oncology clinics of North America 2018; (32(1)):23-36 doi:10.1016/j.hoc.2017.09.003.

    PMID: 29157617
  11. 11

    IL-6 Blockade in Cytokine Storm Syndromes.

    Barrett D

    Advances in experimental medicine and biology 2024; (1448()):565-572 doi:10.1007/978-3-031-59815-9_37.

    PMID: 39117839
  12. 12

    Pelvic unicentric Castleman's disease mimicking accessory spleen: A rare presentation of Castleman's disease, a case report and literature report.

    Emiru ZA, Getahun AM, Kassie YG, et al.

    International journal of surgery case reports 2025; (129()):111177 doi:10.1016/j.ijscr.2025.111177.

    PMID: 40106952
  13. 13

    Unicentric Castleman disease with paraneoplastic pemphigus in a young woman: a case report.

    Lv GT, Zhao YH, Zhao JL, et al.

    Frontiers in medicine 2025; (12()):1749601 doi:10.3389/fmed.2025.1749601.

    PMID: 41625759
  14. 14

    Efficacy and safety of regimens used for the treatment of multicentric Castleman disease: A systematic review.

    Rehman MEU, Chattaraj A, Neupane K, et al.

    European journal of haematology 2022; (109(4)):309-320 doi:10.1111/ejh.13823.

    PMID: 35770616
  15. 15

    Long-term safety of siltuximab in patients with idiopathic multicentric Castleman disease: a prespecified, open-label, extension analysis of two trials.

    van Rhee F, Casper C, Voorhees PM, et al.

    The Lancet. Haematology 2020; (7(3)):e209-e217 doi:10.1016/S2352-3026(19)30257-1.

    PMID: 32027862
  16. 16

    International evidence-based consensus diagnostic and treatment guidelines for unicentric Castleman disease.

    van Rhee F, Oksenhendler E, Srkalovic G, et al.

    Blood advances 2020; (4(23)):6039-6050 doi:10.1182/bloodadvances.2020003334.

    PMID: 33284946
  17. 17

    Taking Control of Castleman Disease: Leveraging Precision Medicine Technologies to Accelerate Rare Disease Research.

    Newman SK, Jayanthan RK, Mitchell GW, et al.

    The Yale journal of biology and medicine 2015; (88(4)):383-8.

    PMID: 26604862
  18. 18

    The application of a multidisciplinary approach in the diagnosis of Castleman disease and Castleman-like lymphadenopathies: A 20-year retrospective analysis of clinical and pathological features.

    Pelliccia S, Rogges E, Cardoni A, et al.

    British journal of haematology 2024; (204(2)):534-547 doi:10.1111/bjh.19171.

    PMID: 37953489
  19. 19

    Complete resection of unicentric Castleman disease in the superior mediastinum: A case report.

    Haro A, Kuramitsu E, Fukuyama Y

    International journal of surgery case reports 2016; (25()):44-7.

    PMID: 27318017
  20. 20

    Castleman disease.

    Carbone A, Borok M, Damania B, et al.

    Nature reviews. Disease primers 2021; (7(1)):84 doi:10.1038/s41572-021-00317-7.

    PMID: 34824298

This orientation guide is for educational purposes only and does not replace professional medical advice. Always consult your hematologist or oncologist regarding your specific Castleman disease diagnosis and treatment plan.

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