Acute eosinophilic pneumonia

High power photomicrograph of acute eosinophilic pneumonia shows a mixed inflammatory infiltrate expanding the alveolar septa and spilling into adjacent air spaces. The inflammatory infiltrate contains numerous eosinophils and mononuclear cells and is accompanied by a fibrinous exudate resembling hyaline membranes (arrow).

High-power photomicrograph shows alveoli containing capillaries within a narrow interstitium. The alveoli are lined with thin, elongated type I pneumocytes (arrow) and smaller numbers of cuboidal type II pneumocytes (dashed arrow).