HOW IS LYMPHANGIOLEIOMYOMATOSIS DIAGNOSED?
The diagnosis of LAM can be difficult because many of the early symptoms are similar to those of other lung diseases, such as asthma, emphysema, or bronchitis. Often the person with LAM first goes to the physician complaining of chest pain and shortness of breath that was caused by a pneumothorax. Some patients first consult their physician because of shortness of breath upon exertion. There are a number of tests the physician can do to confirm or rule out the existence of LAM.
Chest X-ray  This is a simple procedure that provides a picture of the lungs and other tissue in the chest. The chest x-ray is used to diagnose a pneumothorax or presence of fluid in the chest cavity (pleural effusion). The cysts that are suggestive of LAM can be difficult to see on a routine chest x-ray and this test is often not diagnostic. Pulmonary Function Tests  The patient breathes through a mouthpiece into a machine (spirometer) that measures the volume of air in the lungs, the movement of air into and out of the lungs, and the movement of oxygen from the lungs into the blood. This test can be used to determine the effect that LAM has had on lung performance over time, but cannot be used to make a diagnosis. Blood Tests  The patient's blood is analyzed to determine whether the lungs are providing an adequate supply of oxygen to the blood. This is also a useful test for following LAM patients.   Computed Tomography (CT)      Computed Tomography (CT) is the most useful imaging test for diagnosing LAM. The patient lies inside a long, cylindrical structure, and x-ray beams pass through the body from different angles producing multiple images. A computer combines all of these images and provides a multiple two-dimensional picture of the inside of the lungs and chest. This is called a CT scan. CT scans of lungs with LAM On a CT scan, the presence of thin-walled cysts spread relatively uniformly throughout the lungs can indicate LAM. If an angiomyolipoma is also present on the abdominal cuts of the chest CT, the diagnosis of LAM can be made with reasonable certainty. In up to 50% of patients with LAM the finding of an angiomyolipoma on an abdominal CT is diagnostic of LAM. Up to 50% of patients with pulmonary LAM will have this uncommon benign kidney tumor.  (Symptoms of LAM such as lung collapse, fluid in the lungs, shortness of breath, and chest pain, can also aid in the diagnosis of LAM without performing an open lung biopsy.) Lung Biopsy  An open lung biopsy should be performed as a last resort to diagnose LAM. In this procedure, a few small pieces of lung tissue are removed through an incision made in the chest wall between the ribs. Another procedure, thoracoscopy, is also being used in some patients to obtain lung tissue. In this procedure, tiny incisions are made in the chest wall and a small lighted tube (endoscope) is inserted so that the interior of the lung can be viewed, and small pieces of tissue are removed. Both procedures must be done in the hospital under general anesthesia. Recovery from an open lung biopsy takes longer than the less invasive but usually completely adequate thoracoscopic procedure. Another technique, called 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. Bits 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 inadequate for diagnostic purposes in LAM. After the lung tissue is removed, it is examined in a pathology laboratory for the presence of the abnormal muscle cells and cystic changes characteristic of LAM.