Pulmonary alveolar proteinosis is a rare lung disorder characterized by abnormal accumulation of surfactant within alveoli. Clinical presentation is nonspecific, but associated with characteristic radiologic findings and unique management options. We highlight a case of severe pulmonary alveolar proteinosis requiring total lung lavage in a young healthy man.
Case Report
A 37-year-old man with a history of nicotine abuse presented with a 5-month history of progressive dyspnea on exertion and 1 month of nonproductive cough. He denied associated fever, chest pain, and hemoptysis. He endorsed a history of industrial dust exposure from prior employment.
Physical examination and initial laboratory study results were unremarkable. An extensive infectious and rheumatologic workup returned negative. Chest x-ray showed bilateral lung disease, and chest computed tomography demonstrated extensive bilateral ground-glass opacification, most pronounced peripherally, and anterior lobular septal thickening (Figure A). Bronchoalveolar lavage returned positive for periodic acid–Schiff staining, consistent with pulmonary alveolar proteinosis.
The patient was scheduled for total lung lavage with supplemental vest percussion. A double-lumen endotracheal tube was used to lavage 1 lung with warmed saline while independently ventilating the other lung. Initial effluent was noted to be milky, but cleared with subsequent saline infusions (Figure B). The patient was counseled on smoking cessation and discharged after an uncomplicated postprocedural course. Postdischarge laboratory testing revealed antibodies to granulocyte-macrophage colony-stimulating factor, solidifying a diagnosis of autoimmune pulmonary alveolar proteinosis.
Discussion
Pulmonary alveolar proteinosis is a rare lung disease characterized by accumulation of surfactant and apoproteins in distal air spaces. Three main forms of this disorder are recognized: congenital, secondary, and autoimmune, which is the most common subtype.1 In a large cohort study of patients with autoimmune pulmonary alveolar proteinosis, patients presented at a median age of 51 years with exertional dyspnea as the most common presenting symptom. Alternative presenting symptoms included cough, increased sputum production, and fatigue. One third of patients were asymptomatic on presentation, whereas 56% reported a history of smoking and 23% endorsed a history of dust exposure.2
Although physical examination and laboratory studies commonly reveal nonspecific abnormalities, chest radiographs often exhibit alveolar opacities in a “bat wing” distribution. High-resolution computed tomography demonstrates ground-glass opacities and concurrent thickening of intralobular structures, nicknamed “crazy paving.”3 Bronchoscopy with bronchoalveolar lavage frequently exhibits periodic acid–Schiff positive proteinaceous material in alveolar spaces. Lung biopsy and measurement of antibodies to granulocyte-macrophage colony-stimulating factor may help solidify the definitive diagnosis of pulmonary alveolar proteinosis.4Treatment choice is determined by symptoms and gas exchange status: For asymptomatic patients, pulmonary function tests and chest imaging are recommended; for mild symptoms (eg, dyspnea with exertion, cough, and malaise), supportive care and supplemental oxygen are indicated; for severe symptoms (eg, dyspnea with minimal exertion or at rest), total lung lavage, granulocyte-macrophage colony-stimulating factor, and rituximab may be used.5 Total lung lavage should be pursued when patients with pulmonary alveolar proteinosis meet 1 of the following criteria: resting partial pressure of oxygen <65 mm Hg, resting alveolar-arterial oxygen gradient ≥40 mm Hg, or severe dyspnea.3
Conclusions
PAP is a rare pulmonary disease in which excessive pulmonary surfactant accumulates within the alveoli. Symptoms are nonspecific and almost one third of patients are asymptomatic. If PAP is considered in the differential, a CT scan of the chest should be pursued with subsequent bronchoscopy with BAL, PAS staining, and anti-GM-CSF antibody evaluation. Once diagnosis is established, therapeutic decisions can be determined based on the underlying etiology.
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-Alisha Kamboj, BS, Michael Lause, BS, Vijay Duggirala, MD
This article originally appeared in the May issue of The American Journal of Medicine.
