What is Lymphangioleiomyomatosis (LAM)?
Lymphangioleiomyomatosis, also known as LAM, is a rare, progressive lung disease that most commonly affects women in their 30s and 40s. LAM almost never occurs in men.
In LAM, abnormal, smooth muscle-like cells begin to grow out of control in the tissues of the lungs, lymph nodes, lymphatic system and kidneys.
Over time, these cells destroy the normal lung tissue and block the flow of air. The LAM cells also reduce oxygen intake, preventing the lungs from providing oxygen to the rest of the body.
Nearly half of women with LAM develop growths called angiomyolipomas (AMLs) in their kidneys.
Women with LAM may also develop complications in other organs, including growths in the liver, brain and lymph nodes, as well as a buildup of fluid in their chest, abdomen, or pelvis.
What causes LAM?
There are two forms of LAM: sporadic LAM, in which the disease occurs for unknown reasons, and LAM that appears in people with a rare inherited disease called Tuberous Sclerosis Complex (TSC). TSC can cause tumors to grow in the brain, kidneys, heart, eyes, lungs, and elsewhere. As many as 39 percent of women with TSC also have pulmonary LAM.
Doctors do not yet know what causes LAM. The recent discovery of similarities between LAM and TSC has begun to provide some valuable clues about genes involved in both conditions.
There is evidence that the mutation of two genes involved in regulating cell migration and growth are involved in both LAM and TSC. These genes are called TSC1 and TSC2. A defect in the TSC1 or TSC2 gene may prevent cells from behaving normally within the body and may account for abnormal cell growth in the lung and other organs.
Disease Progression in LAM
It used to be thought that women who had LAM would not live more than 10 years following diagnosis. However doctors now know that some women may survive for more than 20 years after diagnosis.
LAM is a progressive disease, which leads to decreased lung function over time. In the early stages of LAM, women can usually go about their daily activities, including attending school, working, and performing common physical activities such as walking up stairs and hills.
As the disease advances, it may be harder for you to be active. You may require supplemental oxygen to enable you to perform your daily activities.
As LAM cells invade your lung tissue, you may be at risk for developing pleural effusions (leaking of fluid into you chest cavity). You may also experience a lung collapse, called a pneumothorax.
Eventually, your lungs may not function properly and you may require evaluation for lung transplantation.
The rate of disease progression varies considerably among women. Some women have aggressive disease and experience rapid progression within a couple of years, while for others, the disease may advance quite slowly for many years.
