BCL-2 EXPRESSION RELIABLY DISTINGUISHES TRICHOEPITHELIOMAS FROM BASAL-CELL CARCINOMAS

Trichoepitheliomas (TE) are benign follicular neoplasms which are freq uently confused with basal cell carcinomas (BCC). It is important to d istinguish these entities precisely, as the treatments and prognoses a re different. To this end, we stained a series of formalin-fixed, para ffin-embedded specimens of unequivocal TE and BCC with antibodies dire cted against bcl-2, an oncogene associated with programmed cell death, and known to be overexpressed in some malignant tumours. The TE showe d staining of tumour cells limited to the outermost layer of the proli feration. The BCC tumour cells demonstrated diffuse staining throughou t the tumour nodules. This difference in staining pattern was then app lied to more equivocal cases, and seemed clearly to separate the entit ies. The observed findings may prove to be of diagnostic help in disti nguishing borderline cases, and also offer some possible explanations for the biological differences between these neoplasms.