Inter- and intra-pathologist variability in histologic diagnoses of lung cancer

To estimate variability and reliability in histologic diagnosis (Dx) of lung cancers, lung cancer preparations were divided into eight equal sets and diagnosed independently by an eight-man pathology panel. Majority Dx (Dx affirmed by more than 4 panelists) was regarded as the consensus Dx of each cancer. The consensus rate of each panelist ranged from 78.8% to 96.1% with an average of 89.4%. The consensus rates were not significantly different among the panelists. Relatively high inter-pathologist agreement was observed in squamous cell carcinoma, adenocarcinoma, and small cell carcinoma. However, regarding large cell carcinoma, there was occasional disagreement among the panelists. Forty-seven cancers were reexamined by the same panelists, with no preliminary announcement, 7 months after the first examination to study the intra-pathologist agreement. The rate of the intra-pathologist agreement ranged from 76.6% to 93.3%. Dx of large cell carcinoma was the most intra-changeable. It was concluded that the histologic Dx of large cell carcinoma was the most inter- and intra-changeable, and the most frequent dissenting Dx from it was poorly differentiated squamous cell carcinoma.