The rate and pattern of bcl-2 and cytokeratin 15 expression in trichoepithelioma and nodular Basal cell carcinoma: a comparative study.

ABSTRACT

CONTEXT Histopathological evaluations can differentiate between clinically resembling trichoepithelioma (TE) and basal cell carcinoma (BCC) unless the biopsy specimens are small or superficial. Previous studies used immunohistochemical evaluation for Bcl-2 and cytokeratin 15 (CK15), in attempts to differentiate between these two entities, with heterogeneous findings. AIMS: This study intended to compare the rate and patterns of Bcl-2 and CK15 expressions between specimens of TE and nodular BCC. SETTINGS AND DESIGN: Case-series including formalin-fixed, paraffin-embedded cutaneous biopsies. SUBJECTS AND METHODS: Twenty-two BCC and 12 TE specimens were stained for Bcl-2 and CK15 and examined microscopically. The rate and patterns of expressions were compared between the two groups. STATISTICAL ANALYSIS USED Statistical analysis was performed using the statistical software (SPSS version 16.0; SPSS Inc., Chicago, IL, USA), Pearson Chi-square, or Fisher's exact tests, wherever appropriate. RESULTS: The two groups were comparable for the expression rate and patterns of Bcl-2 (86.4% 5 central, 14 diffuse in BCC vs. 83.3% 2 central, 8 diffuse in TE; P = 0.59 and 0.54 for rate and pattern, respectively). The rate of CK15 expression was significantly higher in TE specimens (66.7% 4 central, 3 diffuse, 1 peripheral vs. 4.5% 1 central; P < 0.001). The positive likelihood ratio in distinguishing the two neoplasms was 14.7 (95% confidence interval 2.1-103.7). CONCLUSIONS: CK15 but not Bcl-2 staining may help in differentiating between BCC and TE even in BCCs with follicular differentiation.