Pulmonary cysts are characteristic of different diseases that include, but are not limited to, Langerhans cell histiocytosis, lymphangioleiomyomatosis (LAM), and Birt-Hogg-Dubé syndrome. Recently, vascular endothelial growth factor type D (VEGF-D) has been found to be elevated in the plasma of some patients with cystic lung disease. Measurement of serum VEGF-D is a noninvasive test to confirm the diagnosis.
VEGF is an angiogenic growth factor that is usually produced by malignant cells. VEGF-D is a ligand for lymphatic growth factor VEGF receptors 2 and 3 (VEGFR-2 and VEGFR-3). Activation of VEGFR-3 can promote lymphatic formation and spread of malignant tumor cells through the lymphatic system to the lymph nodes.Serum VEGF-D is elevated in patients with LAM compared with healthy controls and patients with other forms of cystic lung disease and emphysema. VEGF-D levels inversely correlate with pulmonary function testing. A serum VEGF-D cutoff of greater than 800 pg/mL has a sensitivity of 73% and a specificity of 100% for LAM in patients with CT confirmed cystic lung disease. However, a VEGF-D level less than or equal to 800 pg/mL does not rule out a diagnosis of LAM.
Recent guidelines by the American Thoracic Society/Japanese Respiratory Society recommend that serum VEGF-D be measured in patients with cystic lung disease suggestive of LAM who have no other clinical or radiological confirmatory features besides lung cysts before proceeding with lung biopsy. They recommend that a threshold of greater than 800 pg/mL to be used to diagnose LAM.
Treatment of these patients with sirolimus causes a sustained reduction in VEGF-D levels.
References
Ataya A, Riley L and Brantly ML, Serum vascular endothelial growth factor D in cystic lung disease. JAMA 2019;321:401-402.
McCormackFX, GuptaN, FinlayGR, et al. Official American Thoracic Society/Japanese Respiratory Society Clinical Practice Guidelines: lymphangioleiomyomatosis diagnosis and management. Am J Respir Crit Care Med. 2016;194 (6):748-761.
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