Classical Hodgkin lymphoma occurring in clusters of nodal marginal zone B-lymphocytes in association with progressive transformation of germinal center. A case report.

We present a case of a classical Hodgkin lymphoma occurring in clusters of marginal zone B-lymphocytes (MZBLs). Most lymphoid follicles possessed hyperplastic germinal centers, while a portion of the follicles exhibited a progressive transformation of the germinal center (PTGC). Clusters of MZBLs showed a perifollicular distribution. The classic Reed-Sternberg cells were found in clusters of MZBLs. A portion of the Reed-Sternberg cells were CD15+, CD20+, CD30+, CD79a+, fascin+, vimentin+, EMA-, and bcl-2-. Some Reed-Sternberg cells were surrounded by CD3+ CD45RO+ CD57-rosettes. In situ hybridization studies demonstrated strong expression of EBER in classic Reed-Sternberg cells and their variants. The overall morphological, immunohistological, and EBV findings confirmed that the present case is a classical Hodgkin lymphoma. The MZBLs were CD20+, CD79a+, sIgM+/-, sIgD-, CD5-, CD21-, CD43-, CD45RO-, and Bcl-2-. Some MZBLs had polytypic intracytoplasmic immunoglobulin. Problems arising in the differential diagnosis between lymphocyte-predominant Hodgkin lymphoma and PTGC have been described. An occasional association between MZBLs clusters and PTGC has been reported previously. This case suggests that classical Hodgkin lymphoma should be added to the differential diagnosis of PTGC.