Derivation of a dysplasia index for epidermal neoplasia.

Measurements have been performed on histological sections of normal, paralesional and affected skin of patients with solar keratoses in an attempt at quantification of the degree of dysplasia. Features of dysplasia, including the epidermal thickness, the nuclear fraction and nuclear size distribution and shape, have been individually derived and incorporated into a formula designed to reflect the degree of dysplastic change within the epidermis. Application of this 'index of dysplasia' has been shown to differentiate lesional epidermis from that of the surrounding and normal non-sun-exposed skin. In addition, this index correlated well with independent dermatopathologists' assessments of the degree of dysplasia.