The Pathological Features of Idiopathic Interstitial Pneumonia - Associated Pulmonary Adenocarcinomas.

To investigate the pathological features of idiopathic interstitial pneumonia (IIP) - associated pulmonary adenocarcinoma.,Surgically resected adenocarcinomas associated with IIP (the IIP group) and adenocarcinomas without IIP (the non-IIP group) were subjected. We here further focused on adenocarcinomas that developed in the honeycomb lesions. Adenocarcinomas in the IIP group were subdivided into two groups, one group included tumors connected to bronchiolar metaplasia in honeycomb lesions (the H-IIP group) and the other included tumors unrelated to honeycomb lesions (the NH-IIP group). Histomorphological appearance, immunohistochemical expression were compared among the H-IIP group, the NH-IIP group, and the non-IIP group.,Most of tumor cells in the H-IIP group showed tall columnar shape that displayed similar features to proximal bronchial epithelium, while tumors in the NH-IIP group and the non-IIP group showed club-like shape that displayed similar features to respiratory bronchiole /alveolar epithelium. The cell differentiation markers, thyroid transcription factor-1 (TTF-1) and Hepatocyte nuclear factor 4 alpha (HNF- 4α), tended to be negative for TTF-1 and positive for HNF- 4α in adenocarcinomas in the H-IIP group. The frequency of EGFR mutations was significantly lower in adenocarcinomas in the H-IIP group, although the frequency of KRAS and ALK mutations did not differ among the three groups.,The IIP-associated pulmonary adenocarcinomas, especially those arising from honeycomb lesions, have distinct pathological features. This article is protected by copyright. All rights reserved.