A patient with long standing, progressive congestive hea failure dies in respiratory distress. The lungs at autopsy are 3 times their normal weight. Histologically, the alveoli show a proteinaceous granular precipitate, enlarged alveolar capillaries, and hemosiderin-laden macrophages. Other inflammatory cells are inapparent. Which of the following is the most likely diagnosis?

These are the characteristic findings of pulmonary edema. The edema fluid is apparent as a proteinaceous granular precipitate after histologic processing of the tissue. Hemosiderin-laden macrophages in the tissue, called "hea failure cells," are the end result of ingestion of red blood cells by alveolar macrophages. Pulmonary edema develops in hea failure when the pulmonary venous pressure rises and the capacity for the tissue to reabsorb the fluid into the venous system is exceeded. In Candida pneumonia, fungal hyphae and spores would be described. In pneumococcal pneumonia, gram-positive cocci (Streptococcus pneumoniae) would be described. In Pneumocystis pneumonia, hat-shaped, silver-stained cysts would be described. Ref: Levitzky M.G. (2013). Chapter 4. Blood Flow to the Lung. In M.G. Levitzky (Ed), Pulmonary Physiology, 8e.