Methods for diagnosing LAM have improved, making it possible to diagnose the disease at an early stage. LAM is diagnosed based on your medical history and the results from diagnostic lung function tests, imaging tests such as high-resolution CT scans, VEGF-D blood tests, or other procedures. To help diagnose your condition, you may want to see a pulmonologist, a doctor who specializes in lung diseases and conditions, who has experience providing care to patients with LAM.
Your doctor will ask you about your medical history to see if you have signs and symptoms related to LAM. Your doctor may ask how long you’ve had symptoms and whether they’ve become worse over time.
Many women may not know they have it because many of LAM’s signs and symptoms are the same as those of other diseases, such as asthma, emphysema, and bronchitis. But, your doctor will want to rule out those other conditions before making a final diagnosis.
Diagnostic tests and procedures
Your doctor may recommend tests to show how well your lungs are working and what your lung tissue looks like. These tests can show whether your lungs are delivering enough oxygen to your blood. You also may have tests to check for complications of LAM.
Lung function tests
- Lung function tests. For lung function tests, you breathe through a mouthpiece into a machine called a spirometer. The spirometer measures the amount of air you breathe in and out. Other lung function tests can show how much air your lungs can hold and how well your lungs deliver oxygen to your blood.
- Arterial blood gas tests. Your doctor may take a blood sample from an artery in your wrist to measure your blood oxygen levels and to determine if you need oxygen therapy.
- Pulse oximetry. For this test, a small sensor is attached to your finger or ear. The sensor uses light to estimate how much oxygen is in your blood.
- Six-minute walk test. This test measures the distance you can walk in six minutes. It can help determine if you need oxygen therapy while exercising.
- Chest x ray. A chest x ray creates a picture of the structures in your chest, such as your heart and lungs. The test can show a collapsed lung or fluid in your chest. In the early stages of LAM, your chest x rays may look normal. As the disease gets worse, the x rays may detect cysts in your lungs and assess how cysts change over time.
- High-resolution CT (HRCT) scan. The most useful imaging test for diagnosing LAM is a high-resolution CT scan of the chest. This test creates a computer-generated picture of your lungs. The picture shows more detail than the pictures from a chest x ray. An HRCT scan can show cysts, excess fluid, a collapsed lung, and enlarged lymph nodes. The test also can show how much normal lung tissue has been replaced by the LAM cysts. HRCT scans of your abdomen and pelvis can show whether you have growths in your kidneys, other abdominal organs, or lymph nodes.
Blood tests for VEGF-D
Your doctor may take a blood sample from a vein in your arm to measure VEGF-D levels. The VEGF-D blood tests test may help confirm the diagnosis of LAM in patients whose HRCT scans show lung cysts that suggest a patient has LAM.
VEGF-D levels of 800 pg/mL (picograms per milliliter) or more can help your doctor confirm that you have LAM. Because you may still have LAM if your levels are less than 800 pg/mL, your doctor may have you undergo other diagnostic procedures that look for LAM cells.
If lung function, imaging, or blood VEGF-D tests cannot diagnose LAM, your doctor may recommend one of the following procedures to collect tissue samples that can be used to detect LAM cells.
- Video-assisted thoracoscopic surgery (VATS). In this procedure, your doctor inserts a small, lighted tube into little cuts made in your chest wall. This lets him or her look inside your chest and snip out a few small pieces of lung tissue. VATS is done in a hospital. The procedure isn’t major surgery, but it does require general anesthesia to make you sleep during the procedure.
- Open lung biopsy. In this procedure, your doctor removes a few small pieces of lung tissue through a cut made in your chest wall between your ribs. An open lung biopsy is done in a hospital. You’ll be given medicine to make you sleep during the procedure. Open lung biopsies are rarely done anymore because the recovery time is much longer than the recovery time from VATS.
- Transbronchial biopsy. In this procedure, your doctor inserts a long, narrow, flexible, lighted tube down your windpipe and into your lungs. He or she then snips out bits of lung tissue using a tiny device. This procedure usually is done in a hospital. Your mouth and throat are numbed to prevent pain. Because only a small amount of tissue is collected, it is possible that this test will not provide enough information.
- Other biopsies. Your doctor also can diagnose LAM using the results from other tissue biopsies, such as biopsies of lymph nodes or abdominal or pelvic lesions.
If your chest imaging tests show that you have pleural effusions, your doctor may order a pleural fluid analysis. For this test, a fluid sample is taken from the pleural space, which is a thin space between two layers of tissue that line the lungs and chest cavity. Doctors use a procedure called thoracentesis to collect the fluid sample. The fluid is studied for the milky substance called chylothorax.
If you’re diagnosed with sporadic LAM, your doctor may advise you to have a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan of your head. These tests can help screen for underlying tuberous sclerosis complex (TSC), a condition that can also cause kidney growths and lung cysts. If a woman who has cysts in her lungs is found to have TSC, the doctor will diagnose TSC-associated LAM or TSC–LAM.