Double staining for CD30 and EBER of case 1.

Immunhistochemical detection of CD30 shows brown membrane staining of multinucleated HRS cells (one marked with an arrow, ABC technique with HRP and DAB as substrate). EBER-ISH positive HRS cells and one small CD30-negative cell (marked by an arrowhead) show blue-black nuclear staining (digoxigenin-labeled EBER probes were detected with AP and BCIP/NBT as substrate). Original magnification, 40×.