Diagnosing LAM

Because many of the early signs and symptoms of LAM are similar to those of other lung diseases, including asthma, emphysema and bronchitis, LAM can be difficult to diagnose.

Often a woman with LAM first goes to her physician complaining of chest pain and/or shortness of breath. Some women first consult their physician because of shortness of breath with physical activity. There are a number of tests the physician can run to confirm or rule out the existence of LAM, evaluate the spread of the disease or determine the extent of lung damage:

High-resolution CT scan - provides a more detailed (two-dimensional) image of the inside of the lungs and chest. It is the most accurate imaging test for diagnosing LAM. A computed tomography, or CT scan, can reveal cysts or abnormal clusters of cells in the lungs, a collapsed lung or enlarged lymph nodes. It can also show the extent to which the cysts have spread. An abdominal CT scan is also recommended, as benign kidney tumors, known as angiomyolipomas, are found in about 40 percent of women with LAM.

VEGF-D blood test – offers the first blood-based diagnostic test for LAM in women.  VEGF-D levels can be used to distinguish LAM from other cystic lung diseases that present with similar High resolution CT scan appearances. When VEGF-D levels are elevated above a certain threshold, surgical biopsy may not be required for diagnosis in some cases. VEGF-D may also be useful as a screening test for LAM in women with TSC.

Lung biopsy - involves removing samples of lung tissue, which are examined under a microscope to look for abnormalities that may indicate LAM. There are several ways physicians can remove lung tissue.

• Thoracoscopy, also called video-assisted thorascopic surgery (VATS), is used to insert a small lighted tube (endoscope) into tiny incisions in the chest wall so that the interior of the lung can be viewed, and small pieces of tissue are removed. This procedure must be done in the hospital under general anesthesia.

• Transbronchial biopsy may also be used to obtain a small amount of lung tissue. A long, narrow, flexible, lighted tube (bronchoscope) is inserted down the windpipe (trachea) and into the lungs. Pieces of lung tissue are sampled using a tiny forceps. This procedure is usually done in a hospital on an outpatient basis under local anesthesia. However, the amount of tissue that can be sampled is usually not adequate to definitively diagnose LAM.

• Open biopsy should only be performed as a last resort to diagnose LAM; recovery is longer than other, less invasive methods. In this procedure, a few small pieces of lung tissue are removed through an incision made in the chest wall between the ribs. This procedure also takes place in the hospital under general anesthesia.

Chest X-ray - takes a picture of the heart, lungs and surrounding tissue. It can show whether there is a collapsed lung or a build-up of fluid around the lungs. The X-ray may show cysts or clusters of cells on the lungs, which are suggestive of LAM; however, this is not the optimal way to diagnose the disease.

Pulmonary function test (PFT) - evaluates how well the lungs are working by measuring the amount (volume) of air inhaled or exhaled, and how much time each breath takes (rate). The patient breathes through a mouthpiece into a machine called a spirometer. The spirometer records the movement of air into and out of the lungs. Although these tests are used to determine the effect LAM has on lung function, they are not typically used for diagnosis.