BCL-2 OVEREXPRESSION IN BASALOID PROLIFERATIONS OVERLYING DERMATOFIBROMAS AND BASAL-CELL CARCINOMAS

Basaloid proliferations overlying dermatofibromas resembling superfici al basal cell carcinomas have been interpreted both as reactive/regres sive and frankly malignant. Basal cell carcinoma is a slow-growing tum our, which so far has been regarded as an actively proliferating lesio n with a high apoptotic activity. We examined immunohistochemically 6 dermatofibromas with overlying simple hyperplasia, 12 dermatofibromas with overlying basaloid proliferations, and 24 basal cell carcinomas f or expression of Ki-67 protein and bcl-2 protein. The Ki-67 labelling index represents an estimate of proliferative activity. Eel-2 protein suppresses apoptosis. The Ki-67 labelling indexes of basaloid prolifer ations, basal cell carcinomas, and normal epidermis were similar (11-1 5%, p<0.05, Mann-Whitney test). Eel-2 protein was expressed in all cel ls of basaloid proliferations, similar to the expression pattern in ba sal cell carcinomas. We suggest that basaloid proliferations overlying dermatofibromas might have achieved a phenotype that equals an early stage of BCC carcinogenesis.