Figure 5a. Desquamative interstitial pneumonia in a 42-year-old man. (a) High-resolution CT scan of the upper lobes demonstrates diffuse ground-glass attenuation, a minor degree of interlobular septal thickening (arrow), and paraseptal emphysema. (b) High-resolution CT scan demonstrates a mosaic pattern of lung attenuation; the abnormal regions are manifested as ground-glass attenuation (arrows). (c) Photomicrograph (original magnification, x12.5; hematoxylin-eosin stain) shows purple macrophages (a) filling the air spaces, interstitial fibrosis (b), and lymphoid aggregates (c). (d) Photomicrograph (original magnification, x50; hematoxylin-eosin stain) reveals an alveolar duct that is filled and distended by pigmented macrophages with purple cytoplasm. Occasional eosinophils (d) and neutrophils are present amidst the macrophages. Interstitial fibrosis is present.