What is lymphangioleiomyomatosis (LAM)?
Lymphangioleiomyomatosis (LAM) is a lung disease caused by the abnormal growth of smooth muscle cells, especially in the lungs and lymphatic system. This abnormal growth leads to the formation of holes or cysts in the lung.
People who have LAM have trouble breathing because it is more difficult to move air in and out of the bronchial tubes. Also, the replacement of normal lung tissue with cysts or holes weakens the ability of the lungs to move oxygen into the bloodstream.
Cysts or holes also put patients at risk for developing pneumothorax, which is a buildup of air or gas in the lining (pleura) of the the lungs, causing a collapsed lung.
Patients with LAM may also develop growths in the kidneys called angiomyolipomas. These are harmless unless they become large, in which case they can cause bleeding.
Who gets lymphangioleiomyomatosis (LAM)?
Lymphangioleiomyomatosis (LAM) almost exclusively affects women. Women who have the disease are usually diagnosed between the ages of 20 and 40. About 30% of women who have tuberous sclerosis also have LAM.
Symptoms and Causes
What causes lymphangioleiomyomatosis (LAM)?
Lymphangioleiomyomatosis (LAM) results from changes in two genes called TSC1 and TSC2. There is a hereditary form of the disease that occurs in patients who have a disease called tuberous sclerosis.
There is a second form of LAM that is not associated with tuberous sclerosis, called sporadic LAM. People who have sporadic LAM also have genetic mutations, but the gene mutations are not hereditary and cannot be passed on to children. The reason these gene mutations occur is unclear.
What are the symptoms of lymphangioleiomyomatosis (LAM)?
The abnormal growth of smooth muscle cells and cysts in the lungs of patients who have lymphangioleiomyomatosis (LAM) can cause the following symptoms:
Diagnosis and Tests
How is lymphangioleiomyomatosis (LAM) diagnosed?
Because symptoms of lymphangioleiomyomatosis (LAM) are similar to those of asthma or bronchitis, many women who have LAM may not realize it right away, or are given the incorrect diagnosis by doctors who are unfamiliar with the disease. Similarly, the cysts in the lung can be misdiagnosed as emphysema.
LAM is usually treated by a pulmonologist, a doctor who specializes in treating lung diseases. It is important that the doctor be familiar with LAM, and diseases that can mimic LAM, to correctly diagnose and treat the disease. The doctor will examine you and ask about your symptoms. The doctor may also order certain tests, including the following:
- High-resolution computed tomography (CT) scan: This scan creates a sharp picture of the lungs to see if the cysts, the main sign of the disease, are present in the lung. This scan can also show if there is any fluid (pleural effusion) around the lungs.
- Lung function tests: In this test, you breathe into a machine called a spirometer to determine how much air you can inhale and exhale and whether your lungs are functioning normally.
- Pulse oximetry: This test uses a small instrument, attached to your finger, to measure how much oxygen is in your blood.
- VEGF-D blood test: This blood test measures the level of a hormone in your body called VEGF-D. If you have cysts in your lung and an extremely high level of VEGF-D, a diagnosis of LAM can be made without need for a biopsy. However, a normal level does not rule out the possibility of LAM.
- CT scan or MRI of the abdomen : These scans create an image of the abdomen and can help make the diagnosis of LAM.
- Lung biopsy: In some cases, it is necessary to obtain a small piece of tissue lung and examine under the microscope to diagnose LAM or to look for other diseases that can look like LAM. This can be done in one of two ways:
- Transbronchial biopsy: With this method, the doctor inserts a lighted tube called a bronchoscope into the lungs through the trachea (windpipe) to take samples of the lung. This can be done as an outpatient and does not involve surgery.
- Video-assisted thoracoscopy: This method is a surgical procedure performed under general anesthesia. The surgeon makes small incisions (cuts) in the chest and inserts a lighted scope to look at the lungs. The doctor can also take biopsies of the lung to examine more closely.
Management and Treatment
How is lymphangioleiomyomatosis (LAM) treated?
There is no cure for lymphangioleiomyomatosis (LAM), but there is now effective treatment to stabilize the disease and prevent it from progressing (getting worse). The drug sirolimus (also known as rapamycin or by the branded name Rapamune® ) is used in patients who show signs that they have lost lung function as a result of LAM. Sirolimus can also be used to shrink large angiomyolipomas of the kidney. In some cases, another medication of the same class, everolimus (Afinitor®, Zortress®), can be used to treat LAM.
Other treatments that may be used in some situations include:
- Oxygen therapy.
- Inhaled medications that help improve the flow of air in the lungs.
- Various procedures to remove fluid from the chest, or to shrink angiomyolipomas.
- Lung transplant (in severe cases of LAM).
Outlook / Prognosis
What is the prognosis (outlook) for patients who have lymphangioleiomyomatosis (LAM)?
Untreated, lymphangioleiomyomatosis (LAM) can be a progressive disease, which means it can get worse over time. With the use of sirolimus, the hope is that the disease can be stabilized for most patients (though not all patients respond to the drug). In the past, the prognosis for patients with LAM was poor, but this is no longer true. Currently, more than 90% of patients are alive 10 years after their diagnosis.
If you've been diagnosed with LAM see your doctors on a regular basis and try to live a healthy lifestyle. Having LAM may cause anxiety and depression as well, so seek emotional support if needed.
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