Chronic Pneumocystosis: Differential Diagnosis of Pulmonary Cystic Lesions

Abstract

Pneumocystis jirovecii pneumonia is an opportunistic fungal disease that typically presents with a subacute onset of fever, cough, and progressive dyspnea, accompanied by a characteristic diffuse bilateral ground-glass pattern on imaging. However, a minority of patients may have an indolent course and atypical radiological features, such as diffuse pulmonary cysts. Diagnosis should be suspected mainly in immunosuppressed individuals and relies on direct visualization of the fungus through bronchoalveolar lavage, sputum examination, or, less commonly, histopathology in uncertain cases. Although new diagnostic methods are under investigation, they remain costly, non-standardized, and difficult to access. Treatment consists of high-dose trimethoprim-sulfamethoxazole for 21 days, with corticosteroid therapy in selected cases (e.g., PaO₂ < 70 mmHg and increased alveolar-arterial gradient). This disease gained prominence during the HIV pandemic in the 1980s and 1990s. Most studies date from that period and are limited to case series and observational designs, lacking controlled randomized trials, which means treatment still relies on established clinical practice.

This pathology gained prominence particularly after the 1980s and 1990s due to the HIV virus pandemic. The main studies date back to that period and are limited to case series and observational studies, lacking controlled and randomized trials, making its treatment based on historical clinical practice.