The use of immunostaining for bcl-2 and CD34 and the lectin peanut agglutinin in differentiating between basal cell carcinomas and trichoepitheliomas.

Fifteen unequivocal basal cell carcinomas (BCC) and ten unequivocal trichoepitheliomas (TE) were studied using the lectin peanut agglutinin (PNA), and the monoclonal antibodies Q bend 10 and bcl-2 oncoprotein directed against the antigens CD34 and bcl-2, respectively, to see whether these markers could be used to differentiate between the two tumors. Ten percent of TE demonstrated a continuous band-like peritumorous staining with PNA and 80% demonstrated a discontinuous band-like peritumorous staining with PNA, with the comparable figures for BCC being 40% and 20%, respectively. In addition, 40% of BCC showed focal areas of pemphigus-like staining in contrast with only 10% of TE. Using the antibody directed against bcl-2, TE demonstrated weak staining mainly confined to the basal layer of tumor cells in 20% of cases and staining of the cells throughout the tumor in 30% of cases. Similarly, BCC also showed staining of the basal layer of tumor cells in 7% of specimens and staining of cells throughout the tumor mass in 40% of specimens studied. Finally, with the antibody Q bend 10 directed against CD34, staining of the immediate peritumoral spindle-shaped cells was observed in 20% of TE compared with 7% of BCC. Despite reports in the literature, we found that none of these three markers can be reliably used to differentiate between TE and BCC.