Histology Course S IV 7 Department of Pathology, University of Zurich Histokurs

S IV 7 pneumocystis carinii pneumonia Grocott further information (German) on HiPaKu
  ICD-10: B59+ J17.3*

29-year-old male, HIV-positive, diffuse lung shadowing. Death following respiratory failure. Autopsy specimen.

Macroscopically: diffuse induration of all lung lobes. Cut surface grey.
- Diffuse changes in the lung.
- Thickening of alveolar septa with lymphocytic and plasma cell infiltrates
- Replacement of type I pneumocytes by type II pneumocytes (so-called cuboid metaplasia)
- 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 seen.
- 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.