Lung: Pneumocystis carinii pneumonia (PCP)

Pneumocystis carinii pneumonia (PCP) This low power view shows a lung with chronic PCP. There are solid areas with fibrosis and clumps of degenerate (blue-staining) Pneumocystis carinii. The air spaces are irregularly emphysematous. This can progress to significant cavitation. H&E stain.