The hallmark cells (and variants) show immunopositivity for CD30 (also known as Ki-1). True positivity requires localisation of signal to the cell membrane or paranuclear region (cytoplasmic positivity is non-specific). Another useful marker which helps to differentiate this lesion from Hodgkin's lymphoma is clusterin. The neoplastic cells have a golgi staining pattern (hence paranuclear staining), which is characteristic of this lymphoma. The cells are also typically positive for a subset of markers of T-cell lineage. However, as with other T-cell lymphomas, they are usually negative for the pan T-cell marker CD3.