ObjectiveTo explore the clinicopathological features of pulmonary alveolar proteinosis (PAP).MethodsA total of 25 patients with PAP who were pathologically diagnosed in West China Hospital of Sichuan University from 2014 to 2018 were collected as the study subjects.ResultsThe 25 patients with PAP were 18–73 years old, with an average age of (42.52±15.79) years. There were 20 males and 5 females. The most common type was autoimmune PAP (15 cases), and secondary PAP (10 cases) were found in patients with pneumonia, tuberculosis, nephrotic syndrome, and pneumoconiosis. The common clinical symptoms of PAP were cough (24 cases), expectoration (20 cases), and progressive difficulty in breathing (11 cases of shortness of breath and 5 cases of dyspnea). The chest CT manifestations included double lung grinding (19 cases), grid-like changes (11 cases), and map-like changes (3 cases). Periodic acid-schiff (PAS) staining and post-digestion PAS staining double positive lipoprotein-like deposits was observed in lung biopsy (in the alveolar cavity) and/or alveolar lavage fluids.ConclusionsPAP has no characteristic clinical symptoms and a long diagnosis period. Clinicians should combine clinical signs, imaging features, and lung biopsy and/or alveolar lavage fluid PAS staining and post-digestion PAS staining to confirm the diagnosis.