Plasmacytic hyperplasia in age-related Epstein–Barr virus-associated lymphoproliferative disorders: A report of two cases

Age-related Epstein–Barr virus (EBV)+B-cell lymphoproliferative disorder (LPD) is a recently recognized entity that occurs in patients over 40 years of age without any known immunodeficiency. However, this entity is thought to be related to the immunological deterioration that is part of the aging process. Histologically, age-related EBV+B-cell LPDs are classified into the polymorphous subtype and large B-cell lymphoma subtypes. However, plasmacytic hyperplasia, which is thought to be the earliest recognizable EBV+PT-LPD, has not been reported among EBV+B-cell LPDs. We report here two cases of age-related EBV-associated LPD and demonstrate the histological evolution. Pathologically, the initial lymph node biopsy specimens from both cases showed the classical Hodgkin lymphoma-like polymorphous subtype. Hodgkin (H) and Reed-Sternberg (RS) cells were CD3−, CD20+, CD15−. CD30+, CD45RB+, and latent membrane antigen-1+. In-situ hybridization (ISH) study demonstrated that numerous H and RS cells contained EBV-encoded small RNA (EBER)+. Repeated lymph node biopsy specimens from each case contained a mixture of lymphoid cells with prominent plasma cell differentiation, including immunoblasts without atypia. A portion of B-immunoblasts were CD30+ and EBER+. As assessed by polymerase chain reaction (PCR) assay, only the initial biopsy specimen in Case 1 displayed a solitary faint immunoglobulin heavy chain (IgH) gene rearrangement, consistent with the presence of a small clonal B-cell population. However, PCR analyses for EBV-genomes demonstrated the same single clonal infection of EBV in the initial and recurrent lymph node lesions in the present two cases. These two cases demonstrated the presence of plasmacytic hyperplasia in age-related EBV+B-cell LPDs, and plasmacytic hyperplasia also appears to be the earliest lesion of age-related EBV+B-cell LPDs.