Pulmonary alveolar proteinosis

Definition

Pulmonary alveolar proteinosis (PAP) is a rare disease of the lungs.

Description

In this disease, also called alveolar proteinosis or phospholipidosis, gas exchange in the lungs is progressively impaired by the accumulation of phospholipids, compounds widely found in other living cells of the body. The alveoli are filled with this substance that renders them less effective in protecting the lung. This may explain why infections are often associated with the disease.

Pulmonary alveolar proteinosis most commonly affects people ages 20-50, although it has been reported in children and the elderly. The incidence is 5 out of every 1 million people. The disease is more common among males.

Causes & symptoms

The cause of this disease is unknown. In some people, however, it appears to result from infection, immune deficiency, or from exposure to silica, aluminum oxide, and a variety of dusts and fumes.

Symptoms include mild shortness of breath associated with a nonproductive or minimally productive cough, weight loss, and fatigue. Acute symptoms such as fever or progressive shortness of breath suggest a complicating infection.

Diagnosis

Physical examination may reveal clubbing of the fingers or a bluish coloration of the skin as a result of decreased oxygen.

A chest x ray may show alveolar disease. An arterial blood gas reveals low oxygen levels in the blood. Bronchoscopy with transtracheal biopsy shows alveolar proteinosis. Specific diagnosis requires a lung biopsy.

Treatment

Treatment consists of periodic whole-lung lavage, a washing out of the phospholipids from the lung with a special tube placed in the trachea. This is performed under general anesthesia.

Prognosis

In some, spontaneous remission occurs, while in others progressive respiratory failure develops. Disability from respiratory insufficiency is common, but death rarely occurs. Repeated lavage may be necessary. Lung transplant is a last resort option.

Prevention

There is no known prevention for this very rare disorder.

Key Terms

Alveoli

The small cavities, or air sacs, in the lungs.

Bronchoscopy

A bronchoscopy is the examination of the bronchi, the primary divisions of the trachea that penetrate the lung, through a tube called a bronchoscope.

Clubbing

Clubbing is the rounding of the ends and swelling of fingers found in people with lung disease.

Remission

Lessening of severity, or abatement of symptoms.

Transtracheal biopsy

A transtracheal biopsy is the removal of a small piece of tissue from across the trachea or windpipe for examination under a microscope.

Further Reading

For Your Information

Organizations

• American Association for Respiratory Care. 11030 Ables Lane, Dallas, Texas 75229. (972) 243-2272. http://www.aarc.org.
• American Lung Association. 1740 Broadway, New York, NY 10019. (800) Lung USA. http://www.lungusa.org.

Gale Encyclopedia of Medicine. Gale Research, 1999.