Findings

• Chest radiograph: Diffuse bilateral ill-defined airspace opacities are seen in a variable distribution.
• Chest CT: CT demonstrates diffuse bilateral ground-glass opacities with superimposed interlobular septal thickening in a “crazy paving” pattern with regions of geographic sparing.

Differential diagnosis

• Pulmonary alveolar proteinosis
• Acute respiratory distress syndrome (ARDS)
• Severe pulmonary edema
• Diffuse alveolar hemorrhage
• Pneumocystis jirovecii infection

Diagnosis: Pulmonary alveolar proteinosis

The patient underwent bronchoalveolar lavage, which demonstrated milky and turbid fluid with thick sediment. Cytology demonstrated large foamy macrophages. Serum antigranulocyte-macrophage colony-stimulating factor (anti-GM-CSF) autoantibodies were positive.