bcl - 2 Expression in Basal Cell Carcinoma , Squamous Cell Carcinoma , Keratoacanthoma , and Trichoepithelioma

Kim, Hyun Cheol; Jang, Min Soo; Chae, Young Soo; Suh, Kee Suck; Kim, Sang Tae

Abstract

BACKGROUND: The bcl-2, gene is a newly described oncogene involved in tumorigenesis by blocking apoptosis, or programmed cell death and overexpression of bcl-2 protein has been reported in several malignant tumors such as lymphoma, breast cancer, and lung cancer. Though keratinocyte-derived skiri tumors are one of the most common human tumors the detailed molecular mechanism of the keratinocytic tumors is not clear. Also, the differentiation between basal cell carcinoma(BCC) and trichoepithelioma(TE) is sometirnes difficult clinically and histologically.
OBJECTIVE
The purpose of this study is to examine whether there is difference in staining pattern of bcl-2 protein in BCC, TE, squamous cell carcinoma(SCC), and keratoacanthoma(KA). We also evaluated the diagnostic value of expression pattern of bcl-2 protein in distinguishing BCC and TE.
METHODS
Routine paraffin sections of formalin-fixed forty-four tissues (19 BCC, 9 SCC, 10squamous cell carcinoma in situ : 5 actinic keratosis [AK] and 5 Bowen disease [BD], 5 keratoacanthoma, and 6 (TE) were labeled with anti-bcl-2 monoclonal antibody using a avidin-biotin peroxidase complex. Normal skin for bcl-2 protein served as negative controls.
RESULTS
The results were as follows. l. In normal skin, bcl- 2 positivity was observed in the epidermal basal layer, the basal layer of follicular infundibuium, the mesenchymal cells of the follicular papillae, and the eccrine glands. 2. All cases of BCC and TE showed a positive cytoplasmic staining for bcl-2 proein, but all cases of SCC, AK, BD, and KA were negative. 3. In staining pattern, of bcl-2 protein, BCC showed diffuse staining throughout the tumor lobules. In TE, the basaloid cells lining the periphery of each tumor nests and the papillary mesenchymal bodies stained strongly.
CONCLUSION
This study shows that BCC express bcl-2 protein, whereas SCC are negative. Our results indicate that proteon from apoptosis mediated by bcl-2 protein may be involved in the neoplastic growth mechanism of BCC. In addition, the ohserved findings in expression pattern of bcl-2 protein in BCC and TE may be of a diagnostic help in distinguishing the borderline cases.