#00066542

(a) Lymph node biopsy showing partial effacement of nodal architecture by polymorphous lymphoid infiltrate (H&E, x 100).(b) Higher magnification demonstrating bare follicles,  expansion of the paracortex by atypical lymphoid cells and prominent vascular proliferation (H&E, x400).

(c) CD20 stain demonstrates residual/reactive B-cell aggregates and follicles.
(d) Immunohistochemistry for CD3 highlights the inconspicuous T-cell infiltrate in the parafollicular areas.

(e-f) CD 10 and PD1 respectively highlights the neoplastic T follicular helper cells seen as rimming the reactive nodules and spilling to the perifollicular regions
(g) CD21 stain demonstrates expansion and irregular proliferation of follicular dendritic cell (FDC) meshworks extending beyond residual follicles.
(h) BCL6 is strong positive in the reactive B cells and weaker in the neoplastic cells.