Epstein–Barr virus‐positive follicular lymphoma

Abstract

A 66-year-old woman presented with left axillary lymphadenopathy. Excisional biopsy was performed. Histological sections showed fragments of an enlarged lymph node with architecture effaced by a vaguely nodular lymphoid neoplasm. The nodules contained predominantly large atypical cells with vesicular chromatin, multiple small nucleoli and variable amounts of cytoplasm, together with a few scattered small cleaved cells (top left). Mitotic figures and apoptotic bodies were variably noted within the nodules. No definite areas of diffuse involvement were noted. The neoplastic cells were positive for CD20, BCL6 (top right), CD10 (focal), CD30 (bottom left), BCL2 and MUM1(focal). In situ hybridisation studies for Epstein–Barr virus (EBV)-encoded small RNAs (EBER) were also performed, showing clusters of positive cells throughout the follicles (bottom right). Lambda immunoglobulin light chain restricted aberrant B cells expressing CD20, CD19 and CD10 (partial/dim) were also detected by flow cytometric analysis. Overall findings were indicative of follicular lymphoma grade 3A. Epstein–Barr virus-positive follicular lymphoma is rare with a prevalence of 2·6%, as reported in the largest case series (Mackrides et al, 2017). Although the majority of cases show EBER-positivity in >75% of tumour cells, low percentage (~5–10%) of EBER-positivity has also been observed. EBV-positivity has been associated with a high grade follicular lymphoma, rapid progression of disease and CD30 expression.