Proliferation indexes--a comparison between cutaneous basal and squamous cell carcinomas.

AIMS To compare differences in cell proliferation indexes and apoptotic indexes between cutaneous basal and squamous cell carcinomas, in an attempt to suggest an explanation for the differences in their biological behaviour. METHODS Forty cases of cutaneous basal cell carcinoma (BCC) and 40 cases of moderately and well differentiated squamous cell carcinoma (SCC) were retrieved from the archives. Sections, 4 microns thick, were cut from formalin fixed, paraffin wax embedded tissue in each case and stained with haematoxylin and eosin. These were then examined for mitotic and apoptotic figures per 1000 cells. Sections from the same cases were also immunostained with the mouse monoclonal antibody Ki67 (MIB1); positive nuclear staining was counted per 1000 cells. RESULTS No significant differences were found between the mitotic indexes and apoptotic indexes in these tumours. There was, however, a significant difference in Ki67 (MIB1) staining, with greater staining in the squamous cell carcinomas. CONCLUSION Estimation of the mitotic and apoptotic indexes did not reveal any differences between these two tumour types. The proliferation indexes, assessed by Ki67 immunostaining, did differ. This may be one of the factors underlying the more aggressive behaviour of SCC.