Pulmonary Pathology: LC22-1 REPRODUCIBILITY OF THE ATS/ERS CLASSIFICATION OF IDIOPATHIC INTERSTITIAL PNEUMONIAS.

Histopathological diagnosis of interstitial pneumonia (IP) requires experiences and is often challenging for general surgical pathologists. In its context, accurate recognition of histopathological usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) patterns along with separation of idiopathic IPs from ones associated with hypersensitivity pneumonia and systemic connective tissue disease are the critical points. Several reports had indicated insufficient interobserver agreement of IP diagnosis, and we also have investigated the interobserver agreement of chronic interstitial pneumonia in various conditions showing that reproducibility of pathological judgment of above points was not greatest. To improve the reproducibility of diagnosis, recent publication of IPF guidelines set criteria of pathological UIP. It indeed helps pathologists to evaluate definite UIP pattern and works well for pulmonary pathologists, however, it still have some confusions and difficulties to the general surgical pathologists. In the course, summary of interobserver agreement along with our own data among pulmonary and general pathologists before and after the new guidelines will be shown. I will also share possible causes of confusion with audience and suggest a few tips for the improved histological assessment.