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Lymphangioleiomyomatosis (LAM)

What is LAM?

Lymphangioleiomyomatosis (LAM) is a rare lung disease that was first described in the medical literature by von Stossel in 1937. An unusual type of muscle cell that invades the tissue of the lungs, including the airways, and blood and lymph vessels, characterizes the disease. Over time, these muscle cells form into bundles and grow into the walls of the airways, and blood and lymph vessels, causing them to become obstructed.

Although these cells are not considered cancerous, they grow without the usual controls within the lungs. Over time, the muscle cells block the flow of air, blood, and lymph vessels to and from the lungs, preventing the lungs from providing oxygen to the rest of the body.

An unusual, frequently asymptomatic , kidney tumor called Angiomyolipoma is found in up to 50% of patients with LAM.

About 2.5% of patients with Tuberous Sclerosis , a genetic disorder, develop a lung disease that is identical to that which occurs in LAM. These patients often have angiomyolipomas of the kidney as well. Although patients with LAM do not develop the central nervous system and skin changes of Tuberous Sclerosis, the similarities in the lung and kidney manifestations of the two diseases have led some investigators to postulate that they may have common causes. For more information contact the National Tuberous Sclerosis Foundation.

Lymphangioleiomyomatosis is pronounced lim-fan je-o-lio-mi o-ma-to sis. Lymph and angio refer to the lymph and blood vessels. Leiomyomatosis refers to the formation of the bundles of the unusual muscle cells.

The cause of LAM is not known.

Do I Have this Disease? (Symptoms)

A common symptom of LAM is shortness of breath (dyspnea) with physical activity. In the early stages of disease, the person with LAM may experience shortness of breath only during strenuous exercise, but as the disease advances, there may be shortness of breath even at rest. Another common symptom is chestpain, and occasionally patients cough up small amounts of blood.

The symptoms associated with LAM are caused by the excessive growth of the muscle cells around the airways, and blood and lymph vessels. The excess muscle cells can block the airways, trapping air in the smallest air compartments in the lung (alveoli) and causing the person with LAM to have difficulty moving air out of the lungs. This results in a breakdown of the lung tissue and the formation of small cysts (air filled cavities).

Cysts near or on the surface of the lung (blebs) can rupture and, as air leaks from the lung into the chest cavity(pneumothorax), the lung or a part of the lung can collapse, causing pain. If the amount of air that leaks out is small, the lung may seal over the space and re-expand itself. If air continues to leak into the chest cavity, however, it may be necessary to re-expand the collapsed portion of the lung by removing the air that has leaked into the chest cavity.

This is an in-patient procedure, done using a tube inserted through the chest wall into the chest cavity.The excessive muscle growth may also block blood vessels in the lung, causing them to become distended with blood and even to rupture. This can result in the patient coughing up blood-stained sputum or blood (hemoptysis).

Obstruction of the lymphatic vessels by the excess muscle growth can lead to leakage of fluid into the chest cavity (pleural effusion). The fluid may be straw-colored (lymph), or fat-containing, milky white (chyle), or pinkish-red if it contains blood. A physician can remove some of this fluid with a needle and syringe to determine its composition and origin. If large amounts of fluid accumulate in the chest cavity, it may have to be removed through a tube surgically inserted into the chest.

It is estimated that 30 to 50 percent of LAM patients will develop leakage of air into the chest cavity (pneumothorax), and up to 80 percent will have leakage of fluid into the chest cavity (pleural effusions). Coughing up blood-stained sputum or blood (hemoptysis) occurs less frequently.

How is LAM Treated?

Because LAM affects almost exclusively women of childbearing age, physicians have thought that the hormone estrogen might be involved in the abnormal muscle cell growth that characterizes the disease, just as it is in the growth of smooth muscle in the uterus in a woman's childbearing years.

Although there is no direct evidence that there is a relationship between estrogen and LAM, the treatment of LAM has focused on reducing the production or effects of estrogen. The response to treatment has been highly individual, and no therapy has been found to be effective for all LAM patients.

Treatments vary in effectiveness from patient to patient, and none have yet been scientifically proven. Oxygen therapy may become necessary if the disease continues to worsen and lung function is impaired. Lung transplantation is considered as a last resort.

A treatment trial is presently being conducted at the University of Cincinnati using a new drug called rapamycin.

Also see:

LAM Handbook [.pdf]
Brochure: Key Facts About LAM [.pdf]

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