Observer variability in the histopathologic diagnosis of lung cancer.

Abstract

The occurrence of intraobserver and interobserver variability in classifying the cellular types of lung cancer was studied in five experienced pathologists, each of whom gave two independent readings of 50 different specimens. Arbitrary rating scales were established to grade the types of discrepancy and other disagreements. With 15 different cellular names available for citation, only one of the 50 slides received readings that were in total agreement for all aspects of the ten interpretations. With the variety of designations reduced to five major histologic groups, the percentages of disagreements of the observers from the consensus reading were 2 per cent to 5 per cent for well differentiated adenocarcinomas and epidermoid carcinomas, 23 per cent to 25 per cent for undifferentiated large cell and small cell carcinomas, and 40 per cent to 42 per cent for poorly differentiated epidermoid and adenocarcinomas. Significant disagreements between the first and second readings of the same slide by the same pa...