Computer-aided application of quantitative microscopy in diagnostic pathology

The quantitative analysis of microscopic images gives objective, consistently reproducible results. The number of applications of such analysis in diagnostic pathology is increasing rapidly. In this chapter, two examples have been given of the development and application of a quantitative microscopic classification rule. Both examples involve admittedly difficult areas of diagnostic pathology, in which considerable disagreement may not only exist among pathologists, but may affect the same pathologist judging the same specimen at different times. These areas are: (1) the discrimination of endometrial hyperplasia from carcinoma, and the grading of endometrial carcinomas; and (2) the preoperative distinction of follicular adenoma from carcinoma of the thyroid in cytologic specimens. With routine use of the classification rule in 148 cases of endometrial hyperplasia or carcinoma received in our laboratory in 1980, with each case judged by one of eight pathologists, there was mild or absolute disagreement in 7.4 percent and 4.7 percent of the cases, respectively (total: 12.1 percent). However, with blind review of one of us (J.B.), there were no absolute and only 3.3 percent mild disagreement. In this series, the quantitative microscopically assigned grades of carcinomas correlated significantly with the depth of invasion in the myometrial wall, whereas the grade routinely indicated by eight pathologists did not. These two facts strongly support the quality and utility of the developed quantitative microscopic rule for classifying endometrial lesions in a diagnostic setting. The rule can also be used to objectively define such endometrial lesions in order to evaluate more accurately their clinical outcome in a prospective study. In the thyroid adenoma cases discussed in the chapter, material from follicular tumors was subjected to quantitative analysis in 1980, again using a classification rule developed in our laboratory. All 10 cases of adenoma were correctly classified, whereas frozen-section diagnosis often gave erroneous or inconclusive results. The quantitative microscopic techniques that we have used are simple, inexpensive, and can be applied in most pathology laboratories. The classification rules can also be used in cases submitted for consultation. The pathologist must use his or her full diagnostic knowledge when applying these techniques. In doing so, he or she will learn that quantitative microscopy has an educative function, automatically results in an increase in the quality of histopathologic work, and supports and sometimes corrects the diagnosis in an objective, consistent way.