Diagnosing LAM

Because many of the early signs and symptoms of LAM (lymphangioleiomyomatosis) are similar to those of other lung diseases, including asthma, emphysema and bronchitis, LAM can be difficult to diagnose. On average, women with LAM have symptoms for 3 to 5 years and suffer an average of 2.2 pneumothoraces before the diagnosis of LAM is made.

There are a number of tests that can confirm or rule out the existence of LAM and evaluate the extent of the disease or of lung damage. These include:

  • Patient profile involves obtaining a full history, including smoking, use of birth control pills, seizure history and family history of tuberous sclerosis complex (TSC). Physical evidence of TSC should be sought carefully. Common skin findings of TSC include:
    • Angiofibromas (acne-like small reddish nodular lesions on the face, especially the nose and cheeks)
    • Subungual fibromas (fibrous nodules arising around or beneath the nails)
    • Shagreen's patches (rough, elevated lesions commonly seen on the lower back)
    • Hypomelanotic macular lesions, also referred to as ash leaf lesions (oval or ash leaf-shaped lesions with decreased pigmentation as compared to the surrounding skin)

    The most common presentation of LAM is progressive dyspnea on exertion (difficulty breathing with physical activity), often in association with a history of pneumothorax (lung collapse) or chylothorax (collection of lymphatic fluid around the lungs). Pneumothorax can also be the event that suggests the diagnosis of LAM in patients who do not have dyspnea on exertion. Other symptoms of LAM include chest pain or coughing.
  • High-resolution CT (HRCT) scan is the most accurate imaging test for diagnosing LAM, providing a correct diagnosis more than 80% of the time. It provides a detailed 2D image of the inside of the lungs and chest, revealing cysts or abnormal clusters of cells in the lungs and whether cysts have spread, a collapsed lung and/or enlarged lymph nodes.

HRCT is recommended:
For patients with known Tuberous Sclerosis Complex (TSC):

    • All females, at least once after the age of 18
    • All patients who present with pneumothorax or chylothorax

For patients who do not have known TSC:

    • All non-smoking women who present with spontaneous pneumothorax
    • All women who present with recurrent spontaneous pneumothorax regardless of smoking status
    • All women found to have an angiomyolipoma, abdominal lymphangiomyoma or chylous effusion
  • Abdominal CT scan or ultrasound is recommended to evaluate for benign kidney tumors (angiomyolipomas), which are found in about 40 percent of women with LAM, and in cases where abdominal cuts of a chest CT are inadequate.
  • VEGF-D blood-based diagnostic test can distinguish LAM from other cystic lung diseases that present with similar HRCT scan appearances. In patients with a compatible HRCT chest, a high VEGF-D value (greater than 800pg/ml) is diagnostic for LAM, and no other confirmatory test is needed in that scenario. Thus, a high VEGF-D level can save the need for an invasive lung biopsy to diagnose LAM. It is important to remember, however, that a normal VEGF-D level does not rule out the diagnosis of LAM. VEGF-D may also be useful as a screening test for LAM in women with TSC.

    VEGF-D blood tests are assessed at Cincinnati Children’s Hospital Medical Center. For questions about submitting samples in the US and internationally, contact:
  • Lung biopsy involves removing samples of lung tissue to examine for abnormalities that may indicate LAM. It is essential that the biopsy specimen be reviewed by an expert pathologist who is familiar with LAM. Lung tissue can be acquired in the following ways:
    • Thoracoscopy, also called video-assisted thorascopic surgery (VATS), involves inserting a small lighted tube (endoscope) into tiny incisions in the chest wall so that the lung can be viewed and biopsied. Procedure is done in a hospital under general anesthesia.
    • Transbronchial biopsy involves inserting a long, narrow, flexible, lighted tube (bronchoscope) down the windpipe (trachea) and into the lungs. Procedure is usually done in a hospital on an outpatient basis under local anesthesia/moderate sedation. However, the amount of tissue that can be sampled is less than in a VATS procedure and may not be adequate to definitively diagnose LAM. Small series suggest that transbronchial biopsy can be diagnostic in 50-60% of cases of LAM, especially when reviewed by an expert pathologist.
    • Open biopsy, or thoracotomy, involves removing tissue through an open incision made in the chest wall. Thoracotomy is a major surgical procedure. This procedure takes place in the hospital under general anesthesia. Open biopsy should only be performed as a last resort to diagnose LAM. Generally, recovery is longer than other less invasive biopsy methods mentioned above.
  • Chest X-ray takes a picture of the heart, lungs and surrounding tissue to show whether there is a collapsed lung or a build-up of fluid around the lungs. While X-ray may show cysts or clusters of cells on the lungs, which are suggestive of LAM, it is not the optimal way to diagnose LAM.
  • 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). Using a machine called a spirometer, the patient’s ability to move air in and out of the lungs is recorded. Although this test is used to determine lung function, it is not typically used to diagnose LAM. PFTs are commonly used to monitor disease progression and response to treatment.

Additional Evaluative Tests

  • CT or MRI of the head should be considered for cortical tubers or other clinically occult manifestations of TSC.
  • An alpha-1 antitrypsin level should be considered to screen for hereditary forms of emphysema.
  • Serologies for Sjogren's syndrome should be considered if xerostomia (dry mouth) and xeroopthalmia (dry eyes) are present.

Diagnosing LAM


Outlines a proposed algorithm for the diagnosis of LAM. CT: computed tomography; TSC: tuberous sclerosis complex; AML: angiomyolipoma; VEGF-D: vascular endothelial growth factor D; TBBx: transbronchial biopsy; VATS: video-assisted thoracoscopic surgery.