[Pulmonary pneumocystosis].

Area of Science:

• Pulmonary Pathology
• Medical Mycology
• Immunocompromised Host Research

Background:

• Pneumocystosis is a significant opportunistic infection, particularly in immunocompromised individuals.
• Hematological neoplasias treated with immunosuppressive therapies are common predisposing factors.
• Understanding the pathogenesis of Pneumocystis carinii pneumonia (PCP) is crucial for clinical management.

Purpose of the Study:

• To investigate the morphological characteristics of Pneumocystis carinii in human lung autopsy cases.
• To elucidate the pathogenesis of lung injury in pneumocystosis.
• To explore the association between pneumocystosis and other opportunistic infections.

Main Methods:

• Macroscopic and microscopic examination of 16 autopsy lung samples.
• Electron microscopy on 5 selected cases.
• Experimental pathogenesis studies in 20 rats.

Main Results:

• Intra-alveolar foamy material primarily composed of Pneumocystis carinii with surface pseudopodia.
• Pneumocystis carinii demonstrated adherence to alveolar walls and to each other via pseudopodia.
• Observed lung pathology included alveolar epithelial desquamation, hyaline membrane formation, and organization of alveolar contents.
• Co-infection with cytomegalovirus pneumonia was noted in 12 cases.

Conclusions:

• Pneumocystis carinii utilizes pseudopodia for attachment, contributing to lung pathology in pneumocystosis.
• The observed pathological changes highlight significant lung tissue damage in severe cases.
• Co-infection with cytomegalovirus is a frequent finding in patients with pneumocystosis.