What is Lymphangioleiomyomatosis or LAM? What is the possible disease course and prognosis of someone diagnosed with LAM?
Lymphangioleiomyomatosis (lim-FAN-jee-o-LYE-o-MY-o-ma-TOE-sis) is a rare, fatal, multi-system disease affecting women in their childbearing years. LAM causes destruction throughout the body, often in the lungs, kidneys and lymphatics. This destruction is attributed to migration, clustering, cell signaling and cell-other cell-cell “LAM cell” abnormalities. Over time, patients may progress to respiratory failure as cysts and nodules take over normal lung. There is no known cure or treatment, and the mechanisms of destruction of lung and other tissues in LAM are poorly understood. One gene defect (TSC2) has been identified in lung tissue, kidney lesions (i.e., angiomyolipomas or AMLs) and circulating cells. Work to identify other mutations and modifier genes is now underway.
Early symptoms of LAM may include shortness of breath, collapsed lung(s), chest pain, abdominal discomfort, and frequent coughing. Over time, women with LAM may experience complications due to leaky lymphatics (chylous or pleural effusions), become less active and require supplemental oxygen full time. Not only is LAM commonly mis-diagnosed as asthma, emphysema or bronchitis, it is also under-diagnosed, as a LAM diagnosis requires a high-resolution CT scan. People with respiratory issues are not routinely scanned due to cost and other factors. There is increasing thought that otherwise healthy, non-smoking women with one or more pneumothoraces (i.e., lung collapses) should have a CT scan to rule out LAM. Progression is variable in LAM. Women with LAM can progress to respiratory failure in less than two years or more than 20 years. We cannot predict who will progress quickly very accurately at this time.
What are the symptoms of LAM?
The most common signs and symptoms of LAM include one or more of the following which are likely caused by the uncontrolled growth of LAM cells: dyspnea or shortness of breath, especially following exertion. At first you may feel short of breath only during strenuous activity. Over time, you may have
- trouble breathing even during rest -persistent cough, sometimes with bloody phlegm
- hemoptysis (coughing up blood) -recurrent pneumothorax (lung collapse)
- chest pain, usually but not always caused by a collapsed lung
- abdominal discomfort or flank pain
LAM also can lead to other serious conditions:
About 6 of every 7 women with LAM develop a collapsed lung (pneumothorax (noo-mo-THOR-aks)) at some point. Sometimes one lung will collapse over and over again. Both lungs can collapse too. This is a serious condition that can be life threatening. A lung that is only partly collapsed may slowly re-expand without treatment, but treatment is often required.
- In 1 out of every 3 women with LAM, a fluid called lymph leaks into the chest cavity and builds up.
- Nearly half of the women with LAM develop growths called angiomyolipomas (AMLs) in their kidneys.
Many women with LAM also have:
- Blood or lymph in their sputum
- Blood in their urine
- Enlarged lymph nodes
- Abdominal swelling
Other diseases can cause many of these signs and symptoms and complications, so it is important that you see a doctor.
What is the relationship between LAM and Tuberous Sclerosis Complex?
LAM cells are very similar to cells found in the lungs of patients with a genetic (inherited) disorder called tuberous sclerosis complex (TSC). As many as 39 percent of women with TSC also have LAM. In TSC, tumors grow in the brain, kidneys, heart, eyes, lungs, skin and elsewhere.
When it is not accompanied by LAM, TSC is usually treatable; however, it can have serious effects including seizures, developmental delays, and kidney disease.
Although LAM is not thought to be inherited, TSC and LAM seem to be affected by mutations in one of two tumor suppressor genes, TSC1 (which encodes a protein called hamartin) and TSC2 (encoding a protein called tuberin).
Who is affected by LAM?
LAM affects women of all races, nations and economic backgrounds. Between 30,000 and 50,000 women worldwide are estimated to have sporadic pulmonary LAM. Approximately 250,000 women worldwide have the form of LAM linked to a genetic disorder called Tuberous Sclerosis Complex (TSC). LAM is understood to be more sex-specific than breast cancer.
- Genetics Home Reference – find information on commonly asked questions such as, “What is LAM?”, “How common is LAM?
- National Heart Lung and Blood Institute – information on how LAM is diagnosed.
- National Heart Lung and Blood Institute – information on treatment for LAM.
- The Merck Manual – find information on what LAM is, signs and symptoms, how it is diagnosed, and treatment options.
- Office of Rare Diseases Research – find information on what LAM is and links to further information.