A grading study of gliomas using computer aided malignancy classification and histologic morphometry.

Forty three cases of astrocytic tumors and mixed gliomas were studied with the aim of evaluating the reproducibility of the Kernohan grading system vis a vis (a) grading using computer-aided malignancy classifier TESTAST 268 and (b) grading by quantitative morphometric evaluation of the various histological parameters of TESTAST 268. These patients were then followed up for variable periods with a maximum of forty months. High inter and intra-observer variability were observed in the Kernohan grading system. TESTAST 268 was found to be simpler, rapid and more reproducible. However, one drawback observed of this system was that it did not completely eliminate inter-observer variability because there was still some subjectivity in assignment of the categorical values against the histological features. Morphometric evaluation of the semi-quantitative assignment values of the 4 histological variables in the TESTAST 268 classifier using Zeiss Morphomat-30 revealed a statistically significant difference between the clusters of the measured quantitative values. A repeat grading using TESTAST 268 and categorical assignment values of histological features derived from the absolute values obtained by morphometry resulted in complete elimination of inter-observer variability. Thus, this study highlights the importance of objectivisation using TESTAST 268 and histologic morphometry in the grading of gliomas. However, since this is a preliminary study on a small number of cases, no cut off values of these measurements have been proposed.