Note hyperplastic type II pneumocytes, wide alveolar septa, and only few alveolar spaces contain some macrophages. HP Interstitial pneumonia. Note widened alveolar septa, with slight mononuclear inflammatory infiltrate and edema. Some macrophages and alveolar epithelial lining cells are in the lumen. There are macrophages and sloughed alveolar pneumocytes within the alveolar spaces.
Some slides have proteinaceous material and in some areas form hyaline membranes.
The alveolar spaces, however, are not packed with cells. The findings are most consistent with an interstitial pneumonia and not a typical bacterial pneumonia in which a neutrophilic response is usually present. These organisms often disseminate in patients that are immunosuppressed. The large red-purple nuclear inclusions, sometimes with a surrounding halo, along with the cytoplasmic inclusions suggest the diagnosis of cytomegalovirus. Herpes does not have cytoplasmic inclusions and often there are multinucleated cells.