Stereological estimation of mean nuclear volume and staining pattern of Ki-67 antigen in keratoacanthomas and...

Keratoacanthomas and squamous cell carcinomas of the skin share many histopathologic features, making differential diagnosis difficult. The aim of this study is to investigate the staining pattern of proliferating cells in keratoacanthomas and squamous cell carcinomas of the skin and to evaluate the value of nuclear morphometric criteria in differential diagnosis. Mean nuclear volume was assessed in 21 keratoacanthomas and 21 squamous cell carcinomas in tissue sections by a stereologic method. Immunohistochemical expression of Ki-67 monoclonal antibody was assessed and the distribution pattern (random or peripheral) of proliferating cells evaluated. Mean nuclear volume (MNV +/- SD) was 590 +/- 293.0 for squamous cell carcinomas and 615 + 305.9 for keratoacanthomas. Statistical analysis showed no significant differences between both groups (p = 0.78) in terms of mean nuclear volume values. Proliferating cells in keratoacanthomas showed a peripheral distribution, whereas there was a random distribution of proliferating cells in squamous cell carcinomas. Our results indicate that quantitative nuclear features are not helpful in making a differentiation between keratoacanthomas and squamous cell carcinomas, while immunohistochemistry with Ki-67 antibody may give useful additional information in differential diagnosis.