LAM: Risk Factors, Symptoms, Diagnosis, Treatment
Lymphangioleiomyomatosis (commonly known as LAM) is a rare, fatal lung disease that affects women in their childbearing years. In LAM, abnormal smooth muscle-like cells proliferate in the lungs, pulmonary airway, parenchyma, lymphatics, and blood vessels, ultimately leading to respiratory failure.1
- Approximately 30,000 to 50,000 women worldwide are estimated to have LAM. There are approximately 250,000 estimated women worldwide with both Tuberous Sclerosis Complex as well as sporadic LAM. Women of all races are affected.2
- LAM cells are very similar to cells found in the lungs of patients with a genetic (inherited) disorder called tuberous sclerosis complex (TSC). 1 As many as 39 percent of women with TSC also have LAM. 3 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. 4 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).
- Symptoms of LAM include: 5
- dyspnea (shortness of breath)
- persistant cough
- hemoptysis (coughing up blood)
- recurrent pneumothorax (lung collapse)
- chest pain
- abdominal discomfort or flank pain
- It can take years to get a definitive diagnosis of LAM. By then the disease is often advanced. LAM is commonly misdiagnosed as asthma, bronchitis or emphysema. Tests that are used to confirm or rule out the existence of LAM include chest X-ray, pulmonary function tests, blood tests, high-resolution computed tomography (CAT) scans (including abdominal area) and lung biopsy.6
Currently there are no effective treatments for LAM. A lung transplant is sometimes an option of last resort (once one becomes dependent on supplemental oxygen), if a matched donor can be found. There is a critical shortage of lungs for transplant. Current estimated survival rates for lung transplants irrespective of underlying disease are up to 80% at 1 year and 60% at 4 years. 7 However, since transplantation does not treat the underlying cause of LAM, and LAM is understood to be metastatic with an origin outside of the lung, LAM is known to recur in the transplanted lungs. Transplant recipients also must take immunosuppressive (anti-rejection) medications indefinitely. These drugs lower immunity to prevent rejection, but also increase the risk of infection and other serious diseases. 8
- Finlay G. The LAM cell: what is it, where does it come from, and why does it grow? Am J Physiol Lung Cell Mol Physiol. 2004 Apr;286(4):L690-3. [PubMed]
- McCormack FX, Young L. Advances in Lymphangioleiomyomatosis. Pulmonary and Critical Care Update. American College of Chest Physicians. Vol 18, Lesson 9. Dec 2005. Accessed: 17 Jan 2006. [http://www.chestnet.org/education/online/pccu/vol18/lessons09_10/lesson09.php]
- McCormack F et al. Pulmonary cysts consistent with lymphangioleiomyomatosis are common in women with tuberous sclerosis: genetic and radiographic analysis. Chest. 2002 Mar;121(3 Suppl):61S. [PubMed]
- US National Institutes of Health. National Institute of Neurological Disorders and Stroke. Tuberous Sclerosis Fact Sheet. Accessed 3 Nov 2005: [http://www.ninds.nih.gov/disorders/tuberous_sclerosis/detail_tuberous_sclerosis.htm Updated Oct 2005]
- Ferrans VJ, Yu ZX, Nelson WK, et al. Lymphangioleiomyomatosis (LAM): a review of clinical and morphologica features. J Nippon Med Sch. 2000 Oct;67(5):311-29 [PubMed]
- Pallisa E, Sanz P, Roman A, et al. Lymphangioleiomyomatosis: pulmonary and abdominal findings with pathologic correlation. Radiographics. 2002 Oct;22 Spec No:S185-98 [PubMed]
- U.S. National Library of Medicine. MedlinePlus Medical Dictionary. Lung Transplant. Accessed 27 Nov 2005: http://www.nlm.nih.gov/medlineplus/ency/article/003010.htm [Updated 5 June 2004]
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