The air sacs in the lung also swell and form small pockets called cysts. As the cysts develop throughout the lungs, LAM causes breathing problems similar to emphysema.
The muscle cells can spread outside the lung, forming noncancerous tumors on organs in the abdomen and pelvis.
What Causes LAM Lung Disease?
No one knows what causes pulmonary lymphangioleiomyomatosis. Estrogen seems to be involved, because women rarely develop LAM before puberty or after menopause. Fewer than 10 men are known to have ever developed LAM lung disease.
Smoking isn't known to cause LAM: more than half of people with LAM lung disease have never smoked.
LAM is so rare that it's unknown how often it really occurs. For example, during a three-year study by researchers, fewer than 250 people with LAM were identified in the U.S. Fewer than 2,000 women are known to have LAM today.
LAM is not cancer, but appears similar to other conditions in which benign tumors grow uncontrollably. LAM lung disease shares some features with a different condition called tuberous sclerosis.
Symptoms of LAM Lung Disease
Most people with LAM lung disease experience shortness of breath. Other symptoms include wheezing and cough, which may be bloody.
Often, people with LAM develop a sudden pneumothorax (collapsed lung). This occurs when one of the cysts near the lung's edge ruptures, allowing inhaled air to compress the lung. A pneumothorax usually causes pain and shortness of breath.
If muscle cells migrate to areas outside the lungs, LAM can cause other symptoms:
Chylous ascites: The flow of lymph is blocked by errant muscle cells. Chyle (milky lymph fluid) builds up in the belly.