Pulmonary alveolar proteinosis
|Pulmonary alveolar proteinosis|
|Classification and external resources|
Micrograph of pulmonary alveolar proteinosis, showing the characteristic airspace filling with focally dense globs referred to as chatter or dense bodies. H&E stain.
|OMIM||265120 610913 610921 610910|
Pulmonary alveolar proteinosis (abbreviated PAP), is a rare lung disease in which abnormal accumulation of surfactant occurs within the alveoli, interfering with gas exchange. PAP can occur in a primary form or secondarily in the settings of malignancy (especially in myeloid leukemia), pulmonary infection, or environmental exposure to dusts or chemicals. Rare familial forms have also been recognized, suggesting a genetic component in some cases.
Signs and symptoms 
The symptoms of PAP include:
The clinical course of PAP is unpredictable. Spontaneous remission is recognized; some patients have stable symptoms. Death may occur due to progression of PAP or due to the underlying disease associated with PAP. Individuals with PAP are more vulnerable to infection of the lung by bacteria or fungi.
Although the cause of PAP remains obscure, a major breakthrough in the understanding of the etiology of the disease came by the chance observation that mice bred for experimental study to lack a hematologic growth factor known as granulocyte-macrophage colony stimulating factor (GM-CSF) developed a pulmonary syndrome of abnormal surfactant accumulation resembling human PAP.
The implications of this finding are still being explored, but significant progress was reported in February, 2007. Researchers in that report discussed the presence of anti-GM-CSF autoantibodies in patients with PAP, and duplicated that syndrome with the infusion of these autoantibodies into mice.
Chest x-rays of affected individuals typically reveal nonspecific alveolar opacities. Diagnosis is generally made by surgical or endoscopic biopsy of the lung, revealing the distinctive pathologic finding. The current gold standard of PAP diagnosis involves histopathological examination of alveolar specimens obtained from bronchoalveolar lavage and transbronchial lung biopsy.
Microscopically, the distal air spaces are filled with a granular, eosinophilic material that is positive with the PAS stain and the PAS diastase stain. The main histomorphologic differential diagnosis is pulmonary edema, which does not have dense bodies.
The first advance in the treatment of Pulmonary Alveolar Proteinosis came in November 1960, when Dr. Jose Ramirez-Rivera at the Veterans' Administration Hospital in Baltimore applied repeated "segmental flooding" as a means of physically removing the accumulated alveolar material.
The standard treatment for PAP is whole-lung lavage, in which sterile fluid is instilled into the lung and then removed, along with the abnormal surfactant material. This is generally effective at ameliorating symptoms, often for prolonged periods. Since the mouse discovery noted above, the use of GM-CSF injections has also been attempted, with variable success. Lung transplantation can be performed in refractory cases.
The disease is more common in males and in tobacco smokers.
In a recent epidemiologic study from Japan, Autoimmune PAP has an incidence and prevalence higher than previously reported and is not strongly linked to smoking, occupational exposure, or other illnesses.
PAP was first described in 1958 by the physicians Samuel Rosen, Benjamin Castleman, and Averill Liebow. In their case series published in the New England Journal of Medicine on June 7 of that year, they described 27 patients with pathologic evidence of periodic acid Schiff positive material filling the alveoli. This lipid rich material was subsequently recognized to be surfactant.
- Shah PL, Hansell D, Lawson PR, Reid KB, Morgan C (January 2000). "Pulmonary alveolar proteinosis: clinical aspects and current concepts on pathogenesis". Thorax 55 (1): 67–77. doi:10.1136/thorax.55.1.67. PMC 1745595. PMID 10607805.
- Stanley E, Lieschke GJ, Grail D, et al. (June 1994). "Granulocyte/macrophage colony-stimulating factor-deficient mice show no major perturbation of hematopoiesis but develop a characteristic pulmonary pathology". Proc. Natl. Acad. Sci. U.S.A. 91 (12): 5592–6. doi:10.1073/pnas.91.12.5592. PMC 44042. PMID 8202532.
- Uchida K, Beck D, Yamamoto T, Berclaz P, Abe S, Staudt M, Carey B, Filippi M, Wert S, Denson L, Puchalski J, Hauck D, Trapnell B (2007). "GM-CSF autoantibodies and neutrophil dysfunction in pulmonary alveolar proteinosis". N Engl J Med 356 (6): 567–79. doi:10.1056/NEJMoa062505. PMID 17287477.
- Monisha Das, MD And Gary A. Salzman, MD (February 2010). "Pulmonary Alveolar Proteinosis: An Overview for Internists and Hospital Physicians". Hospital Practice. 38 (1): 43–49. doi:10.3810/hp.2010.02.277. PMID 20469623.
- Ramirez-Rivera J, Nyka W, McLaughlin J (1963). "Pulmonary Alveolar Proteinosis: Diagnostic Technics and Observations". New England Journal of Medicine 268 (4): 165–71. doi:10.1056/NEJM196301242680401. PMID 13990655.
- Ramirez-Rivera J, Schultz RB, Dutton RE (1963). "Pulmonary Alveolar Proteinosis: A New Technique and Rational for Treatment". Archives of Internal Medicine 112: 173–185.
- Ceruti M, Rodi G, Stella GM, et al. (2007). "Successful whole lung lavage in pulmonary alveolar proteinosis secondary to lysinuric protein intolerance: a case report". Orphanet J Rare Dis 2: 14. doi:10.1186/1750-1172-2-14. PMC 1845139. PMID 17386098.
- Menard KJ (April 2005). "Whole lung lavage in the treatment of pulmonary alveolar proteinosis". J. Perianesth. Nurs. 20 (2): 114–26. doi:10.1016/j.jopan.2005.01.005. PMID 15806528.
- Inoue Y, Trapnell BC, Tazawa R,et (April 2008). "Characteristics of a Large Cohort of Patients with Autoimmune Pulmonary Alveolar Proteinosis in Japan". Am. J. Respir. Crit. Care Med. 177 (7): 752–62. doi:10.1164/rccm.200708-1271OC. PMC 2720118. PMID 18202348.
- Seymour JF, Presneill JJ (July 2002). "Pulmonary alveolar proteinosis: progress in the first 44 years". Am. J. Respir. Crit. Care Med. 166 (2): 215–35. doi:10.1164/rccm.2109105. PMID 12119235.
- Rosen SH, Castleman B, Liebow AA (1958). "Pulmonary alveolar proteinosis". N. Engl. J. Med. 258 (23): 1123–1142. doi:10.1056/NEJM195806052582301. PMID 13552931.
- Pap Foundation/ The american foundation for patients affected by PAP
- EuPAPNet/ The european consortium for PAP
- ORPHANET/ The portal for rare diseases and orphan drugs
- Pulmonary Alveolar Proteinosis: An Overview for Internists and Hospital Physicians