Follicular Hyperplasia, Follicular Lysis, and Progressive Transformation of Germinal Centers: A Sequential Spectrum of Morphologic Evolution in Lymphoid Hyperplasia

Abstract

We studied mantle B-cell and T-cell ingression in hyperplastic follicles (HFs), follicular lysis (FL), and progressive transformation of germinal centers (PTGC) in 19 paraffin-embedded, H&E-, bcl-2-, CD20-, and CD3-stained lymph nodes. We enumerated the T cells (CD3+) and mantle B cells (bcl-2+/CD3-) per 100 cells in 5 high-power fields of each entity (mean +/- SD). Compared with HF, FL had increased numbers of T cells migrating into germinal centers (39.8 +/- 10.0 vs 25.8 +/- 7.8; P < .0001). and a mild increase of mantle B cells (12.3 +/- 11.4 vs 2.1 +/- 1.6; P < .001). PTGC showed an increase of T-cell ingression compared with HF (36.5 +/- 12.1 vs 25.8 +/- 7.8; P < .0001) and more migration of mantle B cells into the follicle than FL (41.0 +/- 22.5 vs 12.3 +/- 11.4; P < .0001). T cells and mantle B cells ingress in FL and PTGC, although the mantle B-cell component predominates in the latter, suggesting that follicular hyperplasia, FL, and PTGC constitute an evolutionary spectrum in resolution of lymphoid hyperplasia with sequential ingression of T cells followed by mantle B cells. The maintenance of bcl-2 expression in mantle B cells in PTGC may cause differential diagnostic pitfalls in florid PTGC vs follicular lymphoma, particularly the so-called floral variant.

Early lesions in lymphoid neoplasia

“…The follicles in PTGC are enlarged, mainly by expansion of the mantle zones. IgD-positive B-cells infiltrate and disrupt the germinal centers, which are fragmented and partially destroyed [11]. PTGC and NLPHL have many features in common causing differential diagnostic problems, but morphological and immunohistochemical differences are also present, e.g.…”

Orbital progressive transformation of germinal centers as part of the spectrum of IgG4-related ophthalmic disease: Clinicopathologic features of three cases

“…Even though the PTGC variant is considered a benign, reactive condition, it has also been described in association with Hodgkin’s lymphoma, particularly nodular lymphocyte-predominant Hodgkin lymphoma 11 . Histologically, PTGC is characterized by irregular enlargement of lymphoid follicles with prominent mantle zone lymphocytes that variably infiltrate germinal centers and may result in follicle lysis 12 . These findings can be highlighted by immunohistochemical stains such as bcl-2 or IgD 3 .…”

F18 fluorodeoxyglucose uptake in progressive transformation of germinal centres

“…PTGC is most commonly seen in lymph nodes in association with reactive follicular hyperplasia [4]. PTGC may precede lymphocyte predominant Hodgkin’s disease (LPHD) or can be present subsequently in lymph node biopsies of lymphoma patients as seen in this case; but the presence of PTGC is not associated definitively with an increased risk of developing HD [5]. …”