Final Diagnosis: Wedge biopsy, RLL: histological features of respiratory bronchiolitis; special stains negative for PCP
Final Diagnosis Comment: Sections from both the right upper and lower lobes show clusters of finely pigmented alveolar macrophages (smoker's macrophages) in centrilobular aggregates as well as dispersed in the more distal lobular alveoli. Attending this is evidence of centrilobular emphysema and some mild small airway thickening with occasional bronchioles harboring a lymphocytic infiltrate that could be called minimal intensity. There is no evidence of parenchymal fibrosis. Morphologically, this is respiratory bronchiolitis.
PCP stains are negative. There is no evidence of a granulomatous reaction or any proteinaceous alveolar exudate.
The clinical and radiological correlation suggests RB-ILD. Typically the pathology in such cases is generally depicted as demonstrating more diffuse changes than is noted in this biopsy but I suspect that we are seeing a variability of sampling.