Paraffin section immunohistochemistry in the diagnosis of Hodgkin's disease and anaplastic large cell (CD30+) lymphomas.

Morphological and immunohistological studies were carried out on a series of 137 lymphomas including CD30+ anaplastic large cell (ALC) lymphomas (48 cases) and non-lymphocyte predominant Hodgkin's disease (HD) (89 cases), with the aim of assessing in situ expression of a combination of antibodies including anti-CD30/BerH2, epithelial membrane antigen (EMA), CD15 and CD45, in addition to other monoclonal antibodies suitable for paraffin tissues. A greater proportion of cases of ALC lymphomas than of HD exhibited positivity for CD45 (91.7% vs 17.6%), EMA (56.2% vs 4.5%), CD43 (53.6% vs 13.1%) and CD45RO (39.5% vs 3.5%), whereas Reed-Sternberg (RS) cells in HD most frequently expressed CD15 (93.2% vs 20.8%) antigen. Moreover, in 35 of 48 (72.9%) ALC lymphomas tumour cells expressed the CD30+, CD45+, CD15-, EMA- or + phenotypic profile, while in the same percentage (62/85) of HD cases RS cells were found to express the CD30+, CD45-, CD15+, EMA- profile. This study suggests that the differential expression of CD45, EMA, and CD15 may be used in the separation of ALC lymphomas and HD. However, co-expression of CD30, CD45 and CD15 antigens by RS cells in HD (14/85 cases, 16.5% in this series) and by tumour cells in ALC lymphomas (9/48 cases, 18.7% in this series) may be encountered in a non-negligible fraction of cases.