71. Pulmonary Alveolar Proteinosis

Definition

Pulmonary alveolar proteinosis (PAP) is a rare lung disease characterized by filling of the distal alveoli with endogenous proteinaceous or floccular material derived from surfactant phospholipids and protein components. This disease presents in two forms: primary (idiopathic) or secondary (resulting from infection, hematologic malignancy(ies) or inhalation of a foreign substance).

Incidence

The incidence of PAP is estimated to be 1:100,000. Males are affected more often by a ratio of 4:1.

Etiology

The etiology of primary PAP is still not known. Secondary PAP is associated with several processes, which lends credence to a causal relationship. The associated processes include inhalation of inorganic/mineral dusts (e.g., silica, titanium oxide, aluminum) or organic materials (e.g., insecticides); hematologic malignancy(ies); myeloid, lysinuric protein intolerance, or HIV infection.

Signs and Symptoms

• Clubbing of digits

• Cor pulmonale (rare)

• Cyanosis (rare)

• Fatigue

• Fine end-inspiratory crackles

• Hemoptysis (rare)

• Intermittent low-grade fever

• Intermittent night sweats

• Malaise

• Persistent dry cough

• Pleuritic chest pain

• Progressive dyspnea

• Pulmonary hypertension

• Weight loss

Medical Management

Medical care of the patient with primary PAP is predicated on the presence or absence of a coexisting infection, the extensiveness of progression of the disease, as well as the degree of physiologic impairment. In the past, treatment consisted of administration of corticosteroids, aerosolized mucolytics, and aerosolized proteinases, but success in this treatment regimen was limited.

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