Discordance between general and pulmonary pathologists in the diagnosis of interstitial lung disease

Interstitial lung diseases (ILDs) often present diagnostic challenges to both the clinician and pathologist. Surgical lung biopsy (SLB) is often pursued in the evaluation of ILD and the clinician uses the histopathologic conclusions to guide management. However, the agreement between general and pulmonary pathologists in histopathologic diagnosis of ILD has not been established.

To determine the agreement between general and pulmonary pathologists in the histopathologic interpretation of ILDs and whether disagreements result in changes in clinical management.

We retrospectively reviewed all patients who underwent SLB for ILD at our institution, between 1996 and 2002. We compared the interpretations of general pathologists to those of pulmonary pathologists to evaluate the degree of inter-rater agreement. We assumed the specialist pathologist represented the "gold standard." We further determined if changes in the histopathologic diagnosis altered clinical management.

Of 83 subjects who underwent SLB, 44 (mean age 58.5 +/- 14.2, 47.7% male) were examined by both general and specialty pathologists. There was poor agreement between the two sets of reviewers. The histopathologic interpretation by the specialist pathologist differed from the generalist in 52.3% of cases (kappa 0.21, P < 0.0001). This high rate of discordance led to frequent (60.0%) changes in clinical management. As a screening test for usual interstitial pneumonia, the observations of the general pathologist had moderate sensitivity and specificity (76.5% and 66.7%, respectively).

General and pulmonary pathologists often differ in their interpretation of the histopathology in ILD. This significant discordance may have important clinical implications for patient care.