Aims Although the tumour cells of Hodgkin lymphoma (HL) are derived from mature B-cells, the lineage infidelity of Hodgkin/Reed–Sternberg cells (HRSs) often causes diagnostic problems. Recently introduced HRS markers are also positive for follicular dendritic cells (FDCs). We investigated the expression of several FDC markers in HL and anaplastic large cell lymphoma (ALCL) and evaluated their diagnostic efficacy.
Methods Eighty-five cases of HL and 52 cases of ALCL were included in this study. Immunohistochemistry was performed for glioma-associated homologue (GLI) 3, class III β-tubulin (TUBB3), fascin, clusterin, γ-synuclein, podoplanin, syntenin, CD21, CD35 and EGFR.
Results HRSs were diffusely positive for GLI3, fascin and TUBB3; the mean positivity rates per case were 94% for GLI3, 82% for fascin, 69% for TUBB3, 17% for clusterin, 17% for γ-synuclein and 14% for syntenin. Podoplanin, CD21, CD35 and EGFR were almost negative. However, the frequency of marker expression was not associated with the histologic subtype or the presence of Epstein–Barr virus (EBV). ALCL showed a similar pattern to HL, but the overall frequency of positivity was lower than that observed in HL. The mean positivity rates were 56% for GLI3, 62% for fascin, 58% for TUBB3 and 21% for clusterin. The other markers were nearly negative. Anaplastic large cell lymphoma kinase positivity did not affect the expression rates.
Conclusions This study confirmed the frequent expression of FDC markers in HL and ALCL. Especially, GLI3, fascin and TUBB3 are the most sensitive markers. Further studies are required to evaluate the association between FDCs, HRSs and ALCL cells.