Pulmonary Alveolar Proteinosis: High yield points

Pulmonary Alveolar Proteinosis (PAP)

a. Lipoproteinaceous material(like surfactant) accumulates within alveoli.
b. There is susceptibility to pulmonary infections, sometimes with opportunistic organisms.
c. In the congenital form, there is mutation in the gene for surfactant protein B or C or the Bc chain of the receptor for GM-CSF.
d. It can be secondary to Hematologic cancers, pharmacologic immunosuppression, inhalation of organic dust (eg., silica) or toxic fumes and certain infections.
e. Acquired PAP is an autoimmune disease targeting GM-CSF.
f. 72 percent patients have a history of smoking.
g. Most patients present with progressive exertional dyspnea of insidious onset and cough. If there is secondary infection, there can also be fever, chest pain, hemoptysis.
h. Physical examination: Some patients have cyanosis, clubbing, inspiratory crackles.
i. Chest X ray: Bilateral air-space disease with an ill-defined nodular or confluent pattern.
j. HRCT: Patchy, ground glass opacifications with superimposed interlobular septal and intralobular thickening, a pattern called "Crazy Paving".
k. The lavage fluid in patients with this disorder has an opaque, milky appearance. It is PAS positive.
l. Electron Microscopy shows that the intraalveolar material consists of amorphous, granular debris containing numerous osmiophilic, fused membrane structures resembling lamellar bodies and tubular myelin. 
m. Acquired PAP has been treated successfully by Whole-lung lavage. 

-VM