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A 64-year-old female with a background of Hodgkin’s lymphoma who was treated with ABVD to complete metabolic response on interim PET scan showed new widespread small volume FDG-avid lymphadenopathy and newly enlarged diffusely avid spleen on end-of-treatment PET scan (Figure 1A). She became progressive anemic and thrombocytopenic. Hb 91 g/L, WBC 12.69 x 10^9 /L, lymphocytes 4.45 x 10^9 /L, platelet 12 x 10^9 /L. Serum protein electrophoresis showed polyclonal raised immunoglobulin without paraprotein. Serum free light chains were elevated with normal K/L ratio. EBV viral load was elevated to as high as 210,000 copies/ml. Peripheral blood film showed rouleaux formation and large atypical lymphocytes with dense chromatin, prominent nucleoli and basophilic cytoplasm (Figure 1B). By flow cytometry, these cells were CD34-CD19+CD5-CD10-CD23+CD20-sIg weak with no light chain restriction.

The lymph node biopsy (Figure 2) showed partial effacement of nodal architecture by a polymorphous population of cells with centroblastic and immunoblastic morphology together with many plasma cells and small and intermediate-sized lymphocytes. Immunohistochemistry for CD20 showed some residual B-cell follicles. Interfollicular areas were expanded by many plasma cells together with many small, medium and occasional large T-cells together with small, medium and large B-blasts. The plasma cells and B-blasts showed polytypic light chain expression. There was no evidence of relapsed Classic Hodgkin lymphoma by morphology. CD30 was noted to weakly stain some transforming blasts. EBER stained moderate numbers of singly scattered small, medium and occasional large lymphocytes.

Bone marrow aspirate showed 20% lymphocytes and 20% plasma cells with no excess blasts, dysplasia or hemophagocytosis. The molecular test showed no evidence of IGH rearrangement. NGS (Archer Variantplex) showed no pathogenic variants. Target FISH and molecular karyotyping showed no abnormalities. She was diagnosed with EBV-driven lymphoproliferative disorder that resembles a polymorphic post-transplantation lymphoproliferative disorder (PTLD). The patient was treated with weekly rituximab for four weeks. As the cytopenia and steroid-dependent fever persisted, her treatment was switched to R-CHOP. She achieved PET/CT complete response, blood count recovery, and negativity of EBV viral load.

EBV-driven LPD may develop when an impaired cytotoxic T-cell response fails to control the proliferation of EBV-infected cells. Here, we reported a rare case of EBV-driven polyclonal LPD after Hodgkin’s lymphoma treatment.