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PubMed This is a summary of 15 peer-reviewed journal articles Updated
Pathology

The Diagnostic Journey: Biopsy, Imaging, and Subtypes

At a Glance

Diagnosing Unicentric Castleman Disease (UCD) typically requires an excisional biopsy to remove the whole lymph node, letting pathologists see its full structure. A full-body PET/CT scan is then essential to confirm the disease is limited to one location and rule out multicentric disease.

Diagnosing Unicentric Castleman Disease (UCD) is a two-step process: first, confirming the unique cellular patterns under a microscope, and second, proving that the disease is limited to just one location in the body [1][2].

The Gold Standard: Excisional Biopsy

While a core needle biopsy (using a needle to take a small tissue sample) is often the first step for many masses, it is usually not enough to diagnose UCD [3][4]. To be certain, pathologists need to see the entire architecture of the lymph node.

  • Why it matters: UCD has complex structures that can be missed in a small needle sample [3].
  • The approach: Doctors prefer an excisional biopsy, which means surgically removing the entire suspicious lymph node or mass [5][6]. This single procedure often serves as both the definitive diagnosis and the primary treatment [5].

Imaging to Rule Out Multicentric Disease

Once the tissue confirms “Castleman’s,” your medical team must ensure it is Unicentric (in one place) rather than Multicentric (in many places).

  • FDG-PET/CT Scan: This is a specialized imaging test where a small amount of radioactive sugar is injected into your blood. UCD masses typically “light up” (show high FDG uptake) because the cells are very active [7].
  • Staging: The PET/CT scan is used for staging—checking your whole body to confirm that only one lymph node region is affected [8][2]. If other areas light up, it may change the diagnosis to Multicentric Castleman Disease (MCD), which requires different treatment [8][9].

The Three Histological Subtypes

Your pathology report will classify your UCD into one of three patterns:

  1. Hyaline Vascular (HV): This is the most common subtype (about 80-90% of cases) [10]. Pathologists look for two classic signs:
    • “Onion-skinning”: Layers of lymphocytes arranged in tight, concentric circles like the layers of an onion [10][11].
    • “Lollipop Follicles”: A blood vessel growing into the center of a lymph follicle, making it look like a lollipop on a stick [10][11].
  2. Plasmacytic (PC): This subtype is less common and often associated with more systemic symptoms like fever or weight loss [12][13]. It is characterized by sheets of plasma cells (immune cells that produce antibodies) [12][13].
  3. Mixed: As the name suggests, this version shows features of both HV and PC patterns in the same node [12][14].

Checklist for Your Pathology Report

When you receive your pathology report, look for these key terms and markers that pathologists use to confirm UCD:

Term/Marker What it Means
CD20 Confirms the presence of B-cells [15].
CD21 & CD23 Markers used to show the “mesh” (follicular dendritic cell network) that is often overgrown in UCD [15][10].
Atrophic Germinal Centers Small, shrunken centers of the lymph node follicles common in the HV subtype [10].
Interfollicular Vascularity An increase in blood vessels between the follicles [10].
Polyclonal Confirms the cells are not “clones” (which would suggest cancer/lymphoma) [1].

Next Steps:

Common questions in this guide

Why do doctors recommend surgery instead of a needle biopsy to diagnose UCD?
A core needle biopsy is often too small to reveal the complex cellular patterns of Unicentric Castleman Disease. Doctors prefer an excisional biopsy, which removes the entire lymph node, to accurately see the complete structure and confirm the diagnosis.
Why do I need a PET scan if they already removed the affected lymph node?
A PET/CT scan checks your entire body to ensure the disease is limited to just one lymph node region. This staging step confirms you have Unicentric Castleman Disease rather than the multicentric form, which appears in multiple locations and requires different treatment.
What does 'hyaline vascular' mean on my UCD pathology report?
Hyaline vascular is the most common subtype of Unicentric Castleman Disease, seen in 80-90% of cases. Under a microscope, it typically shows classic signs like concentric layers of cells resembling an onion skin and blood vessels growing into the center of lymph follicles.
What does it mean if my pathology report says my cells are polyclonal?
A polyclonal result means that the cells in the lymph node are normal, diverse immune cells rather than identical clones. This is a crucial finding because it helps doctors confirm the mass is Castleman disease and rule out cancers like lymphoma.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my biopsy an excisional biopsy (removing the whole node)? If not, is a second biopsy needed to be certain?
  2. 2.Does my FDG-PET/CT scan show any activity in other lymph node regions besides the primary mass?
  3. 3.Does my pathology report mention 'onion-skinning' or 'lollipop follicles'?
  4. 4.What do my CD21 and CD23 stains show regarding the structure of my follicular dendritic cell network?
  5. 5.Based on the plasmacytic features in my report, should I be tested for elevated IL-6 levels or other inflammatory markers?

Questions For You

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References

References (15)
  1. 1

    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
  2. 2

    Castleman Disease of the Thorax: Clinical, Radiologic, and Pathologic Correlation: From the Radiologic Pathology Archives.

    Kligerman SJ, Auerbach A, Franks TJ, Galvin JR

    Radiographics : a review publication of the Radiological Society of North America, Inc 2016; (36(5)):1309-32 doi:10.1148/rg.2016160076.

    PMID: 27618318
  3. 3

    Comparative analysis on efficacy of lymph node sampling through whole node excision versus core needle biopsy: focusing on diagnostic yield for interpretation.

    Singh N, Mishra S, Balasubramanian P, et al.

    Journal of hematopathology 2025; (18(1)):46 doi:10.1007/s12308-025-00662-6.

    PMID: 41087604
  4. 4

    Core needle biopsies and surgical excision biopsies in the diagnosis of lymphoma-experience at the Lymph Node Registry Kiel.

    Johl A, Lengfelder E, Hiddemann W, et al.

    Annals of hematology 2016; (95(8)):1281-6 doi:10.1007/s00277-016-2704-0.

    PMID: 27236576
  5. 5

    A retrospective study of 44 patients with head and neck Castleman's disease.

    Wang T, Chen X, Chen W, et al.

    European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery 2022; (279(5)):2625-2630 doi:10.1007/s00405-021-07065-0.

    PMID: 34480599
  6. 6

    Unicentric Castleman Disease: A Rare Diagnosis of Radiological and Histological Correlation.

    Maqbool S, Javed A, Idrees T, Anwar S

    Indian journal of otolaryngology and head and neck surgery : official publication of the Association of Otolaryngologists of India 2023; (75(2)):975-978 doi:10.1007/s12070-022-03253-4.

    PMID: 36373120
  7. 7

    Castleman Disease Masquerading as the Posterior Mediastinal Mass on 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography.

    Gupta V, Verma R, Malik D, et al.

    Indian journal of nuclear medicine : IJNM : the official journal of the Society of Nuclear Medicine, India 2019; (34(2)):171-172 doi:10.4103/ijnm.IJNM_1_19.

    PMID: 31040538
  8. 8

    Emerging role of 18F-FDG PET/CT in Castleman disease: a review.

    Koa B, Borja AJ, Aly M, et al.

    Insights into imaging 2021; (12(1)):35 doi:10.1186/s13244-021-00963-1.

    PMID: 33709329
  9. 9

    Clinical and pathological characteristics of Castleman disease: an observational study in a Spanish tertiary hospital.

    González-García A, Patier de la Peña JL, García-Cosio M, et al.

    Leukemia & lymphoma 2019; (60(14)):3442-3448 doi:10.1080/10428194.2019.1639168.

    PMID: 31305183
  10. 10

    Hyaline vascular variant of unicentric Castleman disease of the tonsil: a case report.

    Li P, Liu H, Li H, et al.

    Diagnostic pathology 2019; (14(1)):70 doi:10.1186/s13000-019-0836-y.

    PMID: 31253137
  11. 11

    [The clinicopathologic features of unicentric Castleman disease in the children's neck].

    Bi X, Huang R, Ming C, et al.

    Lin chuang er bi yan hou tou jing wai ke za zhi = Journal of clinical otorhinolaryngology head and neck surgery 2024; (38(8)):732-736 doi:10.13201/j.issn.2096-7993.2024.08.011.

    PMID: 39118513
  12. 12

    Unicentric Castleman Disease: Illustration of Its Morphologic Spectrum and Review of the Differential Diagnosis.

    El Hussein S, Evans AG, Fang H, et al.

    Archives of pathology & laboratory medicine 2024; (148(1)):99-106 doi:10.5858/arpa.2022-0404-RA.

    PMID: 36920021
  13. 13

    Unicentric Castleman disease treated with rituximab before surgery: clinicopathologic findings.

    Paulli M, Neri G, Antoci F, et al.

    Annals of hematology 2025; (104(10)):5531-5535 doi:10.1007/s00277-025-06527-3.

    PMID: 40913622
  14. 14

    Historical and pathological overview of Castleman disease.

    Nishimura MF, Nishimura Y, Nishikori A, et al.

    Journal of clinical and experimental hematopathology : JCEH 2022; (62(2)):60-72 doi:10.3960/jslrt.21036.

    PMID: 35474035
  15. 15

    Intracranial Castleman's Disease Mimicking Dural-based Pathologies: A Case Report.

    Moguel AER, Serrano-Rubio A, Gonzalez Soto JA, et al.

    Current medical imaging 2024; (20()):e15734056343564 doi:10.2174/0115734056343564241120113055.

    PMID: 39710920

This page provides educational information on diagnosing Unicentric Castleman Disease and interpreting pathology reports. Always consult your medical team for your official diagnosis and specific medical advice.

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