What islymphangioleiomyomatosis (LAM)?
Lymphangioleiomyomatosis (LAM) is a lung disease caused by the abnormal growth of smooth muscle cells that leads to blockage of the bronchial tubes and lymphatic vessels, and 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 narrowed bronchial tubes. Additionally, the replacement of normal lung tissue with cysts weakens the ability of the lungs to introduce oxygen into the bloodstream, and also makes patients susceptible to developing pneumothoraces (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)?
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.
What causes lymphangioleiomyomatosis (LAM)?
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 changes in these genes, but the gene mutations are not hereditary and cannot be passed on to children. The reason these gene mutations occur remains a mystery.
What are the symptoms of lymphangioleiomyomatosis?
The abnormal growth of smooth muscle cells and cysts in the lungs of patients who have LAM can cause the following symptoms:
- Shortness of breath, which can get worse over time
- Chest pain
- Cough, sometimes with phlegm or blood streaks
- Pneumothorax (collapsed lung)
- Pleural effusions (fluid that accumulates in the chest cavity in which the lung sits)