29-year-old male, HIV-positive, diffuse lung shadowing. Death following
respiratory failure. Autopsy specimen.
Macroscopically: diffuse induration of all lung lobes. Cut surface
- Diffuse changes in the lung.
- Thickening of alveolar septa with lymphocytic and plasma cell
- Replacement of type I pneumocytes by type II pneumocytes (so-called
- Fibrinous exudate with numerous rounded microorganisms which appear
black on Grocott staining (Pneumocystis carinii, revised name: Pneumocystis
jirovecki). These cysts average 4-6 micrometres in diameter and
are located in the extracelluar space. Intracystic bodies can be
- Some hyaline membranes
- Clusters of fibroblast formations beginning to organise
Note: Microorganisms can not be identified in the HE stain. Thus,
a "negative" foam-like exudate can be seen in the alveoli.