Immunohistochemical evaluation of basal cell carcinoma and trichepithelioma using Bcl-2, Ki67, PCNA and P53

Most basal cell neoplasms with follicular differentiation represent a heter ogenous group of tumors. Although may arise anywhere in the skin, these neo plasms commonly occur on die head and neck regions. The majority of these n eoplasms are basal cell carcinomas (BCC) and trichoepitheliomas (TE). Overl apping histopathologic features between these benign and malignant tumors a re occasionally seen which may create problems in rendering a definitive di agnosis. The intent of this investigation was two-fold: 1) to examine wheth er there are quantitative differences of the cellular expression of Bcl-2, Ki67, PCNA and P53 between BCC and TE; and 2) to examine the value of these immunostains in differentiating between BCC and TE. Twenty cases of BCC we re stained with antibodies for Bcl-2, Ki67, PCNA and P53. The positive cell indices and staining characteristic of these immunostains were compared wi th those of 20 cases of TE. The cell indices for each group were analyzed s tatistically utilizing the analysis of variance (ANOVA) technique. Intensit y and patterns of Bcl-2 and P53 expression were similar between BCC and TE. The ANOVA analysis showed no statistically significant differences between cell indices for cases stained with antibodies for Bcl-2 and P53 p=0.49 an d p=0.87 respectively in the two neoplastic groups. There were intense labe lling and generalized patterns of Ki67 and PCNA expression in BCC. Conversl y, Ki67- and PCNA-labelled cells were much fewer in TEs than those noted in BCCs. Additionally, Ki67- and PCNA-positive cells were limited to the peri pheral layers of the neoplastic islands of TEs. There were statistically si gnificant differences between cell indices for cases stained with antibodie s for Ki67 and PCNA (p=0.02 and p=0.05 respectively) in tile two neoplastic groups. BCC and TE exhibited comparable expressions of Bcl-2 and P53 with similar intensity of labelling and patterns of distribution. This suggests possible similar mechanisms of growth regulation in both neoplasms, However , Ki67 and PCNA labelling was noted with significantly increased numbers an d recognizably different patterns in BCCs compared to TEs. This may help ex plain the significant capabilities in tumor proliferation and the aggressiv e behavior of BCC compared to the limited growth potential of TE. Additiona lly, Ki67 and PCNA staining intensity and characteristics may have some val ue in differentiating between BCC and TE.