Usual Interstitial Pneumonia in Lung Resections for Carcinoma
LA Schmidt, EA Medina, KR Flaherty, JL Myers. University of Michigan, Ann Arbor, MI; Universidad Nacional de Colombia, Bogota, Colombia
Background: Usual interstitial pneumonia (UIP) is the defining histologic feature of idiopathic pulmonary fibrosis, a form of progressive lung fibrosis. Studies have observed an increased incidence of peripheral squamous cell carcinomas (SCC) in patients with UIP. We determined the incidence of UIP in lungs resected for SCC and non-SCC lung carcinomas.
Design: This is a retrospective observational case-based study in which hematoxylin and eosin stained slides from all lung resections (lobectomy, bilobectomy, or pneumonectomy) for primary lung SCC from 1999-2009 (n=164) were reviewed. A cohort of resected non-SCC carcinomas (n=183) was also reviewed. Slides were evaluated for tumor type and tumor location. Tumors were classified as peripheral if they were located <3 cm from visceral pleura without involving a cartilaginous airway. Sections taken from non-neoplastic lung were assessed for degree of fibrosis, honeycomb change, respiratory bronchiolitis, emphysema, and osseous metaplasia and classified as UIP, probable UIP (>25% fibrosis and honeycomb change but without characteristic patchwork distribution), or not UIP. Clinical data was abstracted from medical records.
Results: UIP/probable UIP was diagnosed in 9.1% of SCC resections and 5.5% of non-SCC resections (p=0.02; see Table). UIP/probable UIP was present in 7.2% of resections for peripheral tumors and 7.1% of resections for central tumors regardless of tumor type; there was no statistically significant increase in UIP/probable UIP between peripheral and central SCC or between peripheral and central non-SCC. UIP was originally diagnosed in only 6.3% and 30% of affected patients with SCC and non-SCC, respectively.
|SCC without UIP (n=148)||SCC with UIP/probable UIP (n=15)||Non-SCC without UIP (n=173)||Non-SCC with UIP/probably UIP (n=10)|
|Mean age , yrs (range)||68 (44-85)||68 (60-78)||66 (26-85)||70 (54-87)|
|Mean size, cm (range)||3.7 (0.6-12)||3.3 (0.8-9)||3.0 (0.5-13)||4.1 (1-6.7)|