Cytokeratin 10 and Ki-67 nuclear marker expression in keratoacanthoma and squamous cell carcinoma.

The most frequent consideration in the clinical and histologic differential diagnosis of keratoacanthoma is squamous cell carcinoma. In the present study, cytokeratin 10 expression and proliferation rate as measured by Ki-67 expression were compared between 50 clinically and histologically diagnosed keratoacanthomas and 50 squamous cell carcinomas. Tissue sections from the skin were immunohistochemically stained with anti-cytokeratin 10 and anti-Ki-67 monoclonal antibodies. The distribution of cytokeratin 10 expression and proliferative cell count were analyzed. Study results showed higher cytokeratin 10 expression in keratoacanthomas than in squamous cell carcinomas and different distribution of staining in the two entities. The analysis of cytokeratin 10 expression showed a much wider range of values and statistically higher median (p<0.001) in keratoacanthomas than in squamous cell carcinomas. Additionally, the proliferation index of keratinocytes as measured by Ki-67 expression was significantly higher in squamous cell carcinomas than in keratoacanthomas (p<0.01). These results may prove helpful in histologic differentiation of these disorders.