Panlobular emphysema of the bilateral lower lobes due to complete destruction of secondary pulmonary lobules. Lower lobe predominance indicates a hematogenous insult.
The differential diagnosis for bilateral lower lung panlobular emphysema is alpha-1-antitrypsin deficiency and talc-containing Ritalin (methylphenidate) injection.
This patient had a documented history of Ritalin injection, causing the so-called Ritalin lung.