Key Facts
- LAM or lymphangioleimyomatoisis is a rare lung disease caused by abnormal growth of smooth muscle cells, particularly in the lungs, lymphatic system and kidneys.
- LAM primarily affects women, usually when they are of childbearing age.
- It is a progressive disease, meaning it gets worse over time, but there are treatment options available to relieve symptoms and prevent complications.
What Causes LAM
LAM is caused by the changes (mutations) in one of two genes called tuberous sclerosis complex genes, TSC1 and TSC2. There are two types of LAM.
- The first form is hereditary and occurs in people who have inherited the rare genetic disease called tuberous sclerosis complex. This is called TSC-LAM and is most common.
- The second form, called Sporadic LAM or S-LAM, results in a genetic change occurring for an unknown reason. This form of LAM is not hereditary.
How LAM Affects Your Body
When you have LAM abnormal smooth muscle cells begin to grow out of control in the lungs, lymph nodes, kidneys and sometimes other organs. This can lead to organ tissue damage and impair function.
- LAM cells can result in the formation of cysts on your lungs. This can make breathing difficult and reduce your ability to take in oxygen. If a cyst ruptures, it can lead to a collapsed lung, also known as pneumothorax.
- In the lymphatic system, a part of your immune system that keeps your body fluids in balance, LAM can cause blockages resulting in fluid build up in the chest and abdomen that will require draining.
In the kidneys, it may result in the formation of benign (non-cancerous) fat-containing lesions called angiomyolipomas.
Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.
Page last updated: February 3, 2026
