Differentiation of Basal Cell Carcinoma From Trichoepithelioma by the Immunohistochemical Method Using bcl - 2 Protein

Lee, Sang Hyub; Suh, Ho Suk; Choi, Jee Ho; Sung, Kyung Jeh; Moon, Kee Chan; Koh, Jai Kyoung

Abstract

BACKGROUND: It is important to distinguish trichoepitheliomas from basal cell carcinomas because, despite the similarity of clinical and histological findings, the treatments and prognoses are different. bcl-2 is a newly characterized protooncogene that has been shown to suppress programmed cell death(apoptosis), which is involved in tumorigenesis, and its expression has been demonstrated within tumor cells in a variety of neoplasms.
OBJECTIVE
We tried to evaluate the staining pattern of bcl-2 protooncogene in basal cell carcinomas and trichoepitheliomas.
METHODS
We examined cases of basal cell carcinomas and trichoepitheliomas with the immunohistochemical method of labelled streptavidin-biotin complex in paraffin-embedded sections using the antigen retrieval method.
RESULTS
1. The bcl-2 staining pattern in basal cell carcinomas was diffuse throughout the tumor lobules, but multifocal absences of bcl-2 staining were identified in sites of follicular differentiation. Also, inhomogeneous staining patterns were observed around the cystic, glandular structure of several subtypes of basal cell carcinoma. 2. The trichoepitheliomas showed staining of tumor cells limited to the outer layers of the tumor lobules. 3. Normal skin showed staining of basal keratinocytes, rnelanocytes in the epidermis, and eccrine gland secretory cells, basal layer of follicular structures, and dermal hair papilla in the dermis.
CONCLUSION
The immunohistcchemical bcl-2 staining is helpful for the differentiation of basal cell carcinomas from trichoepitheliomas particularly in borderline cases and the explanation of different biologic courses for the two diseases. Further investigation of bcl-2 staining in other malignant skin diseases should be undertaken, and its practical adaptation should be more widely used in borderline cases.