Rare Presentation of Pulmonary Alveolar Proteinosis Causing Acute Respiratory Failure

Abstract

Pulmonary alveolar proteinosis (PAP) is a rare condition characterized by dysfunctional alveolar macrophages, which ineffectively clear surfactant and typically cause mild hypoxemia. Characteristic Computed Tomography findings are septal reticulations superimposed on ground-glass opacities in a crazy paving pattern, with a clear juxtaposition between affected and unaffected parenchyma. While traditionally PAP was diagnosed via biopsy, bronchoalveolar lavage (BAL) is usually sufficient; the fluid appears milky, and on microscopic examination there are foamy macrophages with eosinophilic granules and extracellular hyaline material that is Periodic Acid-Schiff positive. Standard therapy is whole lung lavage (WLL), although novel treatments are under development. The case presented is a 55-year-old woman with six months of progressive dyspnea, who developed hypoxemic respiratory failure requiring mechanical ventilation; she had typical findings of PAP on imaging and BAL. WLL was ultimately successful in restoring adequate oxygenation. Respiratory failure of this magnitude is a rare finding in PAP.

Figure 1

Initial chest radiograph, posterior-anterior view, showing hazy airspace opacification of the lower lobes bilaterally.

Figure 2

CT of the thorax depicting diffuse bilateral ground-glass opacities with intralobular septal thickening; the findings are reported by the radiologist to be a crazy paving pattern.

Figure 3

Photograph of the BAL fluid, demonstrating an opaque, milky appearance.

Figure 4

PAS-stained BAL preparation showing PAS positive globular material and supporting a diagnosis of PAP (magnification 400x).

Figure 5

Papanikolaou stained BAL preparation showing abundant globular orangeophilic material along with a few macrophages and leukocytes (magnification 400x).

Figure 6

Posterior-anterior chest radiograph after three sessions of WLL, demonstrating improvement of the infiltrative process.