Nuclear morphology and histological grading of oral squamous cell carcinoma (OSCC). A morphometric study

Histological grading of oral squamous cell carcinoma (OSCC) is usually evaluated in a semiquantitative way and this causes a low grade of reproducibility of this prognostic evaluation. The aim in this preliminary phase is to investigate the relation between nuclear shape (studied by an analytical procedure) and histological grading to evaluate the weight of nuclear shape and dimension in grading formulation. Nine cases of OSCC were studied (3 cases of G1, G2 and G3 respectively) with 20 nuclei for each case. All the tumors were localized on the lip. Histologic grading according to the Bryne system was performed. Each nucleus was submitted to a morphometrical study by the SAM (Shape Analytical Morphometry) system which, apart from dimensions allows us to evaluate nuclear contour irregularities and nuclear shape asymmetry. Nuclei of squamous cell carcinoma show a progressive increase in dimensions (area, perimeter and diameter) from G1 to G3. Nuclei of G3 carcinoma are characterized by the most irregular shape. Size differences (mean value) are significant to differentiate G1 nuclei from G2 and G3 nuclei while shape parameters are useful in distinguishing G3 nuclei from G1 and G2. Multivariate discriminant analysis showed that by using only nuclear parameters it is possible to correctly classify about 80% of nuclei. This study, using quantitative methods, confirmed nuclear pleomorphism to be the most important feature in grading evaluation.