Successful Whole-Lung Lavage in Anti-GM-CSF-Negative Pulmonary Alveolar Proteinosis: A Case Report

BACKGROUND Pulmonary alveolar proteinosis (PAP) is a rare lung disease characterized by the accumulation of surfactant within the alveoli. Its reported prevalence ranges from 3.7 to 40 cases per million. Because of its rarity and nonspecific clinical presentation, PAP is frequently misdiagnosed as more common respiratory conditions such as recurrent pneumonia. Accurate etiological classification is essential but can be challenging in routine clinical practice. CASE REPORT We report the case of a 79-year-old female non-smoker who presented with dyspnea and a history of unsuccessfully treated multiple pneumonia episodes. A computed tomography (CT) scan revealed a crazy paving pattern. Bronchoscopy showed the bronchoalveolar lavage fluid (BALF) had a milky appearance and became progressively opaque upon standing. The diagnosis of PAP was made based on a characteristic CT pattern and typical BALF analysis. Anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibodies were negative, excluding autoimmune PAP. Extensive evaluation did not identify secondary causes such as hematologic disorders, immunodeficiency, chronic infection, or relevant environmental exposure. Genetic testing for hereditary PAP was not available; therefore, this subtype could not be definitively excluded. The patient subsequently underwent whole-lung lavage (WLL), leading to resolution of her symptoms and radiological features after 6 months of follow-up. CONCLUSIONS PAP can present with nonspecific respiratory symptoms and be misdiagnosed as recurrent pneumonia. Diagnosis relies on characteristic CT findings and BALF analysis, while determination of the PAP subtype requires systematic exclusion of autoimmune and secondary causes. This case highlights the diagnostic challenges of PAP classification in routine clinical practice.