Pulmonary alveolar proteinosis.

The term pulmonary alveolar proteinosis (PAP) comprises a heterogeneous group of rare disorders characterized by abundant deposition of surfactant- and lipoproteins in the alveoli. The autoimmune form accounts for 90% of cases and is characterized by the presence of GM-CSF autoantibodies. Secondary PAP is associated with several underlying conditions, mainly hematologic malignancies, infections and inhalation exposure, and is GM-CSF antibody negative. Several conditions can mimic PAP, in particular the radiological findings: the crazy paving pattern on high resolution computed tomography (HRCT) is common also to infections, neoplasms, and other interstitial lung diseases. Bronchoalveolar lavage (BAL) typical findings and the detection of serum GM-CSF antibodies are usually sufficient for the diagnosis of PAP. Whole lung lavage (WLL) is still the gold standard for treatment of PAP and is followed by complete remission in about 50% of cases. Inhalative treatment with GM-CSF alone or in combination with WLL could represent the future approach for patients with autoimmune PAP refractory to WLL alone. The anti CD-20 antibody rituximab represents a further promising approach for autoimmune PAP. The treatment of secondary PAP should be focused on the underlying disease.