Lymphangioleiomyomatosis (LAM): Cysts in the Lungs, and the Medicine That Slows Them
Last updated September 4, 2026.
Lymphangioleiomyomatosis, almost always called LAM, is a rare lung disease in which abnormal cells grow in the lungs, lymphatics, and kidneys, and thin-walled cysts gradually replace normal lung tissue. It affects women almost exclusively, usually appearing between puberty and menopause, and while there is no cure, a daily medicine slows it meaningfully and most women live full lives for decades after diagnosis.
What is happening in the lungs
LAM cells carry a genetic change that leaves a growth-control switch stuck on. In the lungs they cluster around airways and blood vessels, forming cysts that crowd out the tissue that moves oxygen. The same cells can cause fatty kidney growths called angiomyolipomas, which are usually watched rather than treated. LAM comes in two forms: one linked to tuberous sclerosis complex, an inherited condition, and a sporadic form that appears in women with no family history and no other features of that condition. Neither form is passed directly to children in the sporadic case.
LAM is slowed by a daily tablet and two firm rules: no smoking, no estrogen. Sudden chest pain and breathlessness mean the ER, and after one collapsed lung, ask about the procedure that prevents the next.
Start a free AI doctor consult →How it shows up
The two classic arrivals are breathlessness that creeps up over years, often first noticed on stairs or exercise, and a collapsed lung out of nowhere, sometimes the very first sign. A persistent dry cough, chest pain, and wheezing that mimics asthma are common, and some women get fluid collecting around the lungs. Because LAM is rare and its symptoms look like asthma or COPD, many women see several doctors before a chest CT scan shows the unmistakable pattern of cysts. A blood test for a protein called VEGF-D often confirms it without a biopsy.
How it is managed
The cornerstone is sirolimus, a daily tablet that turns the stuck growth switch down. It stabilizes lung function in most women who need it, and it also shrinks kidney growths when they cause trouble. Oxygen helps some, inhalers help a minority, and pulmonary rehabilitation keeps fitness up. Two rules sit above the rest: do not smoke, and avoid estrogen, which feeds LAM cells, so estrogen-containing contraception and hormone therapy are replaced with alternatives. A collapsed lung is treated urgently and usually followed by a procedure to stick the lung lining closed, because recurrences are common. Lung transplantation exists for advanced disease and works well, but most women on modern treatment never reach it. Monitoring lung function and symptoms on a schedule, usually at a center that knows the disease, is the long-term rhythm.
- Estrogen is off the table. Estrogen-containing contraception and hormone replacement feed LAM cells. Progestin-only and non-hormonal options exist, and your team can lay them out.
- A collapsed lung can recur. Sudden sharp chest pain and breathlessness mean the emergency department immediately. After a first collapse, ask about the preventative lining procedure, because second collapses are common without it.
- Pregnancy needs planning, not avoidance. Many women with LAM have safe pregnancies, but lung function and disease activity shape the timing and the monitoring, so plan it with the LAM team rather than improvising.
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Common questions
Why did I get LAM? Did I inherit it?
Most LAM is sporadic, caused by a genetic change that arises in the body's cells rather than one passed from parents, so it is not inherited and is not passed to children. A minority of cases occur with tuberous sclerosis complex, which is inherited, and your team can test for that form.
Will I need a lung transplant?
Most women treated with sirolimus never do. Transplantation exists for advanced disease and works well in LAM, but modern treatment has made it the exception rather than the destination.
Why do I have to change my birth control?
Estrogen stimulates LAM cell growth. Estrogen-containing pills, patches, and hormone replacement are swapped for progestin-only or non-hormonal methods, which control fertility without feeding the disease.
Can I get pregnant with LAM?
Many women with LAM have successful pregnancies, but pregnancy raises the stakes for lung complications and hormone changes. It should be planned with your LAM team, with lung function checked before and monitored during.
Is LAM cancer?
No, though its cells behave in a low-grade cancer-like way, growing where they should not. It does not spread or destroy tissue the way cancer does, and chemotherapy is not the treatment; sirolimus, a growth-signal blocker, is.
What should I do about air travel and exercise?
Most women with LAM fly and exercise safely, but cysts raise a small risk of lung collapse with pressure changes, so discuss flying and scuba diving with your team. Exercise is encouraged at whatever level breathlessness allows, and pulmonary rehabilitation helps you find that level.