Rationale Lymphangioleiomyomatosis (LAM) is a rare disease of the lungs and lymphatics occurring almost exclusively in women, usually presenting before menopause. It is characterised by progressive cystic destruction of the lung parenchyma, obstruction of lymphatics, airways, and often progressive respiratory failure. Recent diagnostic criteria require lung biopsy in addition to HRCT in the absence of other features such as tuberous sclerosis, renal angiomyolipomas or chylous effusions. The clinical course of LAM varies significantly, and there are no good predictors of clinical progression. Vascular endothelial growth factor D (VEGFD) has been found to be increased in the serum of LAM patients but its role as a biomarker has never been examined prospectively.
We aimed to see if:
VEGF-D reduces the need for lung biopsy for diagnosis using a proposed cut off with an estimated test sensitivity for LAM of 86%, specificity of 91%, and a positive likelihood ratio of 9.6.
VEGF-D is a useful predictor of severity when correlated with lung function data.
Results Serum samples were taken from 34 LAM patients and 12 healthy controls and a significant difference in VEGF-D levels was seen (Patient median=768 pg/ml, IQR=417.6–1509, control median=329.5, IQR=288.6–489.0, p=0.0082, Mann–Whitney U test). However, using the proposed cut off of 574 pg/ml by Young et al (2008), only 1 patient in our cohort with a diagnosis of “probable” LAM would have avoided the need for a lung biopsy to confirm diagnosis. When correlated with lung function, only TLCO demonstrated a statistically significant negative correlation with VEGFD levels (r2=0.2143, p=0.0131).
Conclusions Though an interesting research tool, the value of VEGFD as a biomarker in LAM has not been clearly demonstrated and there is currently insufficient evidence to advocate its role either to aid in diagnosis or prediction of outcome in LAM.