Pulmonary Alveolar Proteinosis

Pulmonary Alveolar Proteinosis

National Organization for Rare Disorders, Inc.


It is possible that the main title of the report Pulmonary Alveolar Proteinosis is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Phospholipidosis
  • PAP
  • Alveolar Lipoproteinosis

Disorder Subdivisions

  • Idiopathic Pulmonary Alveolar Proteinosis
  • Secondary Pulmonary Alveolar Proteinosis
  • Congenital Pulmonary Alveolar Proteinosis

General Discussion

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder characterized by the accumulation of grainy material consisting mostly of protein and fat (lipoproteinaceous material) in the air sacs of the lungs (alveoli). Breathing often becomes progressively difficult. The disorder occurs in different forms, ranging from mild to severe, and can affect individuals of any age. PAP may occur secondary to many environmental exposures or underlying diseases. However, most cases of PAP occur for no known reason (idiopathic or primary PAP). An extremely rare form of PAP occurs in newborns (congenital PAP).


The symptoms of idiopathic and secondary PAP vary greatly from case to case. Some individuals may exhibit no apparent symptoms (asymptomatic). Others may experience difficult breathing (dyspnea) and shortness of breath upon exertion. Breathing difficulties often become progressively worse. A dry, chronic cough may develop that is sometimes associated with mucous development (sputum).

Some affected individuals may develop general symptoms such as fatigue, weight loss, chest pain and a general feeling of ill health (malaise). In rare cases, affected individuals may experience the coughing up of blood (hemoptysis), rounding and swelling (clubbing) of the tips of the fingers, and cyanosis, a condition in which abnormal bluish discoloration of the skin occurs because of low levels of circulating oxygen in the blood.

Some individuals with PAP become susceptible to repeated respiratory infections. In some cases, PAP may progress to cause life-threatening respiratory failure. In other cases, the symptoms may resolve without treatment (spontaneous resolution).

An extremely rare form of PAP occurs in some newborns (congenital PAP). Affected infants may experience difficulty breathing (dyspnea). Additional symptoms that occur less frequently include chest pains, failure to thrive, and fever, which is usually associated with respiratory infection. Life-threatening complications such as respiratory distress often occur early during infancy.


Most cases of PAP occur for no known reason (idiopathic).

Some researchers believe that idiopathic PAP may actually be an autoimmune disorder. Autoimmune disorders are caused when the body's natural defenses against "foreign" or invading organisms begin to attack healthy tissue for unknown reasons. In some cases of PAP, antibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF) have been found. GM-CSF is a protein that assists in the production certain cells (i.e., granulocytes and macrophages). Researchers speculate that antibodies against GM-CSF results in impaired function of macrophages within the alveolar sacs, which, in turn, results in the accumulation of lipoproteinaceous material.

Researchers have determined that some cases of PAP occur secondary to a variety of causes including exposure to certain chemicals or minerals such as silica, aluminum or insecticides; underlying malignancy such as lymphoma or leukemia; immunosupressive medications; and certain infections such as nocardiosis or cytomegalovirus.

An extremely rare form of PAP occurs at birth (congenital PAP). Researchers believe this form of PAP is inherited as an autosomal recessive trait. Genetic diseases are determined by two genes, one received from the father and one from the mother.

Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%.

Affected Populations

PAP affects men more often than women by a ratio of 2-4 to 1. The disorder may occur in individuals of any age from newborns to the elderly. Most cases affect adults between the ages of 20-50. More than 400 cases have been reported in the medical literature.

Standard Therapies


A diagnosis of pulmonary alveolar proteinosis is suspected based upon a thorough clinical evaluation, a detailed patient history, identification of characteristic symptoms and a variety of specialized tests including bronchoalveolar lavage (BAL). During a BAL a narrow tube (bronchoscope) is slid down the windpipe and a sterile solution is passed through the tube washing out (lavaging) cells. After removing the tube, the cells can then be studied.

Tests that determine how well the lungs are functioning may also be performed. Chest x-rays and computed tomography (CT scan) may also be used to assist diagnosis by revealing extensive white patches within the lungs. During a CT scan, a computer and x-rays are used to create a film showing cross-sectional images of internal structures such as the lungs.

A diagnosis of PAP may be confirmed by transbronchial lung biopsy, a procedure during which a thin, flexible tube (bronchoscope) is inserted through the nose or mouth and guided through the windpipe to the lungs to remove tissue for microscopic examination.


The treatment of PAP varies from case to case depending upon the age of an affected individual and severity of the disease. Approximately one-third of individuals with idiopathic PAP will improve without treatment (spontaneous remission). The other two-thirds may be treated by a whole lung lavage, a procedure in which one lung is cleansed with a salt solution while the other is pumped with pure oxygen. In some cases, the procedure may need to be performed once; in others it may need to be repeated many times over several years.

In secondary PAP removal and avoidance of the causative agent (e.g., silica exposure) or treatment of the underlying disorder may improve symptoms.

Treatment for congenital PAP is symptomatic and supportive. According to the medical literature, successful lung transplantation has been used to treat some infants with congenital PAP. Genetic counseling may be beneficial for families of individuals with the congenital form of PAP.

Investigational Therapies

Researchers are studying granulocyte-macrophage colony-stimulating factor (GM-CSF) as a potential treatment for individuals with PAP. Initial studies have demonstrated some improvement of symptoms with treatment with GM-CSF. However, more research is necessary to determine the long-term safety and effectiveness of this treatment for individuals with PAP.

Lung transplantation has been used to treat adults with PAP as a last resort. According to the medical literature, in some cases, PAP has recurred in adults who have received lung transplantation.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:




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