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Lymphangioleiomyomatosis (LAM)

Lymphangioleiomyomatosis (LAM)

Lymphangioleiomyomatosis (LAM) is a rare lung disease that almost always affects women during their reproductive years. The average age it starts is around 34 years. AAbnormal tissue growth in the lungs causes cysts, which lead to breathing problems. Other affected organs may include the kidneys, uterus and lymphatic system. LAM may occur sporadically (sLAM) or in association with the genetic disease tuberous sclerosis complex (TSC).

The cause of LAM is unknown. Sporadic LAM (sLAM) occurs in about one woman in a million, although the exact incidence is not known. LAM can also occur in women who have a condition known as tuberous sclerosis complex (TSC). To date, there is no known cure for LAM.

Abnormal growth of lung cells

LAM usually targets the lungs. The smooth muscle cells of the lungs begin to ‘overgrow’, forming clumps and cysts (fluid-filled sacs) around the airways, blood vessels and lymph vessels. As the disease progresses, these abnormal growths damage healthy lung tissue and interfere with breathing.

Symptoms

In the early stages, the symptoms of LAM resemble those of more common respiratory conditions such as asthma, bronchitis or emphysema. The symptoms of LAM may include:

 Shortness of breath

 Breathlessness during physical exertion

 Chest pain

 Cough

 Coughing up viscous white sputum

 Coughing up blood (haemoptysis)

 Progressive worsening of symptoms over time.

Other body parts may be affected

LAM can also cause problems in other areas of the body, such as:

Kidneys – benign (non-cancerous) growths. About one woman in three who has LAM has kidney tumours, which are called angiomyolipomas (AMLs).

Abdomen and pelvis – cysts or tissue masses called lymphangioleiomyomas that develop behind the lining of the abdomen (peritoneum).

Lymph nodes – enlargement, which is usually harmless.

LAM complications

LAM may cause serious complications including:

Collapsed lung (pneumothorax) – caused by changes in air pressure inside the chest. Typically, a cyst bursts and leaks air from the lungs into the chest cavity. In mild cases of partial collapse, the lung may reinflate by itself. In other cases, surgery is needed. Sometimes, the condition is chronic and the affected lung may collapse over and over again. Pneumothorax is relatively common in people with LAM.

Pleural effusion – build-up of fluid in the space between the lungs and the lung membrane (pleura). The fluid may be an unusual type called chyle, producing a chylothorax. About one woman in three affected by LAM has an abnormal leakage of lymphatic fluid into the chest cavity.

Bleeding tumours – the kidney tumours (angiomyolipomas, or AMLs) may bleed. Symptoms include back pain and blood in the urine.

The link with tuberous sclerosis complex (TSC)

LAM develops in about 40 percent of women who have a disease called tuberous sclerosis complex (TSC). It also occasionally develops in men with this disease. TSC is a rare genetic disorder that involves the formation of root-like growths in the brain and, occasionally, other organs such as the kidneys, heart, liver and lungs. These growths begin to form in the brain prior to birth and interfere with brain functioning. In most cases, the cause is a spontaneous gene mutation within the developing baby. In about 20 per cent of cases, the mutated gene is inherited.