Progressive Transformation of Germinal Centers

Progressive Transformation of Germinal Centers

Pei Lin, MD

The PTGC follicle image is 4-5x larger than normal reactive follicles image. Note the expanded mantle zone image of the PTGC follicle.

High-power magnification shows the center of a PTGC follicle. Centroblasts and centrocytes are intermixed with small mature lymphocytes from the mantle zone. However, LP cells are not present.



  • Progressively transformed germinal centers

  • Progressively transformed follicular centers



  • Viral cause suspected



  • PTGC can occur at any age but is common in young adults

    • Median age: 28 years

    • ˜ 20% of cases occur in children

  • M > F

  • PTGC usually involves peripheral lymph nodes

    • Cervical lymph nodes are most commonly involved (50% of cases)

    • Axillary and inguinal lymph nodes less common

  • PTGC can be the predominant change in lymph nodes prompting biopsy

  • Patients with PTGC can present ± symptoms

    • Most frequent presentation is asymptomatic and localized lymphadenopathy

    • Generalized lymphadenopathy can occur in subset of patients

      • Adolescents who present with viral-like illness

      • Patients with autoimmune diseases

    • PTGC can be incidental finding in patients with lymphoma

    • PTGC can be detected at initial diagnosis or after therapy

    • Interval between PTGC and lymphoma can be > 10 years

    • PTGC also rarely can precede diagnosis of lymphoma

  • PTGC usually spontaneously resolves but can recur

    • Same or different lymph nodes

    • Recurrence occurs more often in children than in adults

  • PTGC is not associated with HIV infection


  • Excellent


Radiographic Findings

  • Lymphadenopathy in subset of patients


Histologic Features

  • Follicles with PTGC are usually large

    • 4-5x larger than normal reactive secondary follicles

  • PTGC is usually focal; involves only a few follicles in lymph node

  • Process of PTGC appears to proceed in stages

    • Initially germinal centers become hyperplastic

      • “Starry sky” pattern can occur but is unusual

    • 2-3 germinal centers per follicle fuse together

    • Mantle zone B cells infiltrate and disrupt germinal centers

    • Eventually germinal centers disappear

    • Centroblasts and follicular dendritic cells are scattered among small mantle zone B cells

  • Follicles involved by PTGC appear to be at different stages (i.e., asynchronous)

  • PTGC is almost always accompanied by follicular hyperplasia

    • Interfollicular hyperplasia often present

  • PTGC follicles can show Castleman-like changes (uncommon)

  • Clusters of epithelioid cells can surround PTGC follicles

    • More common in pediatric cases

  • PTGC can coexist with Hodgkin or non-Hodgkin lymphoma

    • Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is most common

      • No data to support PTGC as precursor of NLPHL

    • Other lymphoma types uncommonly associated with PTGC

      • Classical Hodgkin lymphoma (nodular sclerosis or mixed cellularity)

      • Plasma cell myeloma

    • PTGC may involve same lymph node involved by lymphoma or different lymph node

  • In generalized cases of PTGC, histologic findings are more florid

    • Rarely associated with lymphoma

Cytologic Features

  • Mixed population of small and large lymphocytes

    • Small round lymphocytes are mantle zone B cells and reactive T cells

    • Germinal center centrocytes and centroblasts

  • No LP cells; no Hodgkin-Reed-Sternberg (HRS) cells

  • No plasma cells, neutrophils, or eosinophils



  • Preserved B-cell and T-cell compartments of lymph node

    • Prominent follicular pattern

  • In PTGC follicles

    • Germinal centers

      • B-cell antigens (±), T-cell antigens (-)

      • CD10(±), Bcl-6(±), Bcl-2(-)

      • Disruption of follicular dendritic cells that are CD21(±), CD23(±)

    • Mantle zones

    • B-cell antigens (±), T-cell antigens (-)

    • IgD(±), Bcl-2(±)

    • CD10(-), Bcl-6(-)

  • T cells are relatively few in PTGC follicles

Flow Cytometry

  • No evidence of monoclonal B-cell population

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Progressive Transformation of Germinal Centers
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