What is Pulmonary Lymphangioleiomyomatosis
(LAM)?Lymphangioleiomyomatosis (LAM) is a rare lung disease that
was first described in the medical literature by von Stossel in 1937. The
disease is characterized by an unusual type of muscle cell that invades the
tissue of the lungs, including the airways, and blood and lymph vessels. 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 act somewhat like
cancer cells in that they grow uncontrollably throughout the lung. Over time,
the muscle cells block the flow of air, blood, and lymph to and from the lungs,
preventing the lungs from providing oxygen to the rest of the body.
Kidney tumors that are often asymptomatic may also be found in patients with
LAM.
Lymphangioleiomyomatosis is pronounced lim - fan' je - o - li' o - 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.
How Common is LAM?LAM affects almost
exclusively women of childbearing age, although several cases have been reported
in which the disease was thought to have developed after menopause. The
international literature also includes reports of a few cases in men.
The precise number of people who have LAM is not known. It has been estimated
that there may be up to several hundred women in the United States with the
disease.
It also has been suggested that LAM has become more common during the past 5
to 10 years, although it may be that doctors are doing a better job of
diagnosing it.
What Are The Symptoms of Lymphangioleiomyomatosis?
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 chest pain, 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 this 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.
What Is The Course Of
Lymphangioleiomyomatosis?LAM is generally progressive, leading
to increasingly impaired lung function. The rate of development can vary
considerably among patients. As the disease advances, there is more extensive
growth of muscle cells throughout the lung and repeated leakage of fluid into
the chest cavity (pleural effusions). As an increasing number of cysts are
formed, the lung takes on a honeycomb appearance.
The survival time following the diagnosis of LAM is uncertain. It has been
reported to be less than 10 years, but new reports show patients living more
than 20 years after diagnosis. The reason for the apparently increased survival
time is unknown.
How Is Lymphangioleiomyomatosis Diagnosed?
The diagnosis of LAM can be difficult because many of the early
symptoms are similar to those of other lung diseases, such as asthma, emphysema,
or bronchitis. Often the person with LAM first goes to the physician complaining
of chest pain and shortness of breath that was caused by a pneumothorax.
Some patients first consult their physician because of shortness of breath
upon exertion.
There are a number of tests the physician can do to confirm or rule out the
existence of LAM.
- This is a simple procedure that provides a picture of the lungs and other
tissue in the chest. The chest x-ray is used to diagnose a pneumothorax or the
presence of fluid in the chest cavity (pleural effusion).
- The patient breathes through a mouthpiece into a machine (spirometer) that
measures the volume of air in the lungs, the movement of air into and out of
the lungs, and the movement of oxygen from the lungs into the blood.
- The patient's blood is analyzed to determine whether the lungs are
providing an adequate supply of oxygen to the blood.
- Computed tomography (CT) is the most definitive imaging test for
diagnosing LAM.
- The patient lies inside a long, cylindrical structure, and x-ray beams
pass through the body from different angles, producing multiple images. A
computer combines all of these images and provides a 3-dimensional picture of
the inside of the lungs and chest. This is called a CT scan.
- On a CT scan, the presence of thin-walled cysts spread relatively
uniformly throughout the lungs usually means LAM.
- Although it is sometimes possible to diagnose LAM based on the above
tests, the most definitive test for the diagnosis of LAM is an open lung
biopsy. In this procedure, a few small pieces of lung tissue are removed
through an incision made in the chest wall between the ribs.
- Another procedure, thoracoscopy, is also being used in some patients to
obtain lung tissue. In this procedure, tiny incisions are made in the chest
wall, and a small lighted tube (endoscope) is inserted so that the interior of
the lung can be viewed, and small pieces of tissue are removed.
- Both procedures must be done in the hospital under general anesthesia.
Another technique, called transbronchial biopsy, may also be used to obtain a
small amount of lung tissue. A long, narrow, flexible, lighted tube
(bronchoscope) is inserted down the windpipe (trachea), and into the lungs.
Bits of lung tissue are sampled, using a tiny forceps. This procedure is
usually done in a hospital on an outpatient basis under local anesthesia. It
is less reliable than an open lung biopsy because the amount of tissue that
can be sampled is sometimes inadequate for diagnostic studies.
- After the lung tissue is removed, it is examined in a pathology laboratory
for the presence of the abnormal muscle cells and cystic changes
characteristic of LAM.
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 evidence that there is a relationship between estrogen
and LAM, the treatment of LAM has focused on reducing the production or effects
of estrogen. Two treatments used are administration of medroxy-progesterone, a
drug containing the hormone progesterone, or removal of the ovaries
(oophorectomy). The response to treatment has been highly individual, and no
therapy has been found to be effective for all LAM patients.
Oxygen therapy may be necessary if the disease continues to worsen and lung
function is impaired.
For LAM patients with severe disease, lung transplantation is an established
therapy. One year survival following transplant is approximately 70 percent, and
3-year survival is approximately 50 percent.
What Is The Effect Of LAM on The Patient's
Lifestyle?In the early stages of the disease, most patients can
go about their daily activities, including attending school, going to work, and
performing common physical activities, such as walking up a hill. In more
advanced stages, the patient may have very limited ability to move around and
may require oxygen full-time.
Patients with LAM should follow the same healthy lifestyle recommended for
the general population, including eating a healthy diet, getting as much
exercise as they can, as well as plenty of rest, and, of course, not smoking.
Traveling to remote areas where medical attention is not readily available or to
high altitudes where the blebs can expand and rupture should be considered
carefully before undertaken.
In patients with normal lung function, there is probably no increased risk
associated with pregnancy. However, in patients with compromised lung function,
pregnancy is not advised.
There do not appear to be complications associated with oral contraceptives,
but this issue should be discussed with the patient's pulmonologist and
gynecologist.
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