Fractal dimensions of the epithelial-connective tissue interfaces in premalignant and malignant epithelial lesions of the floor of the mouth.

Irregularity of the shape of epithelial-connective tissue interfaces is a well-recognized feature of malignant and premalignant epithelial lesions, yet few attempts have been made to assess it objectively. The fractal dimension (as a measure of irregularity of shape) of the epithelial-connective tissue interface of premalignant, malignant and normal epithelial tissues of the floor of the mouth was measured using box counting and boundary trace methods. The lowest value found was 0.99 (a normal mucosa using the box method) and the highest 1.61 (a carcinoma using the trace method). Analysis of the values against the histopathologic diagnoses (normal, keratosis with mild dysplasia, keratosis with moderate/severe dysplasia and squamous cell carcinoma) showed no significant difference between normal epithelium and that from keratosis with mild dysplasia, but these were significantly different from the two other diagnoses, which were significantly different from each other. The study illustrated the potential of fractal analysis for providing objective diagnostic information about irregular shapes in histopathology.