Figure 3a. Atypical adenomatous hyperplasia in a 53-year-old woman. (a) Thin-section CT image of the right lung shows an 11-mm well-defined nodular ground-glass opacity without a solid component in the lower lobe. (b) Photomicrograph (original magnification, x100; hematoxylin-eosin stain) shows thickened alveolar walls lined by an intermittent single layer of atypical cuboidal pneumocytes.