Epstein–Barr virus‐driven bone marrow aplasia and plasmacytosis mimicking a plasma cell neoplasm

Abstract

We report a 19-year-old woman who initially presented to her general practitioner with symptoms of tonsillitis. Over 24 h she became tachycardic and septic. In the emergency department, blood results demonstrated Hb 85 g/l, WBC 0·27 × 109/l, platelet count 22 × 109/l, neutrophils 0·02 ×109/l, creatinine 65 μmol/l and calcium 2·09 mmol/l. She was admitted to the intensive care unit with neutropenic sepsis for intravenous antibiotics and inotrope support. Further blood tests demonstrated vitamin B12 555 ng/l, folate 5·7 μg/l and human immunodeficiency virus (HIV) 1+2 serology negative. A blood film confirmed pancytopenia with no blast cells or evidence of dysplasia. The pancytopenia persisted and she was investigated with a bone marrow aspirate and trephine biopsy. There were 56% plasma cells on analysis of the bone marrow aspirate. The trephine biopsy sections demonstrated significant haemopoietic aplasia, along with a moderate interstitial infiltration with plasma cells, some of which were binucleated or trinucleated (top left). The majority of nucleated cells were CD138-positive with appearances consistent with multiple myeloma (top right). However, there was no light chain restriction with equal staining for kappa (bottom left) and lambda (bottom right). Serum electrophoresis showed polyclonal hypergammaglobulinaemia with no paraprotein or immunoparesis. Analysis of serum free light chains was unremarkable: kappa 40·49 mg/l, lambda 65·86 mg/l with a kappa/lambda ratio of 0·615. Epstein–Barr virus (EBV) polymerase chain reaction revealed 3580 EBV DNA copies/ml and a diagnosis of haematopoietic aplasia with polytypic marrow plasmacytosis secondary to EBV infection was made. She was treated with 40 mg dexamethasone for 4 d resulting in complete resolution of her cytopenias. This case re-emphasises the importance of confirming clonality in patients with a suspected plasma cell neoplasm. A very marked marrow plasmacytosis may still be non-clonal and reactive in nature.