To make a clinical diagnosis of LAM, characteristic high-resolution CT (HRCT) feature—thin-wall cystic air sacs evenly distributed in bilateral lobes, surrounded by normal pulmonary tissues (9)—plus one or more of the following: presence of TSC, angiomyolipomas, chylous effusions, lymphangioleiomyomas, or elevated serum vascular endothelial growth factor-D (VEGF-D) ≥800 pg/ml, is required (10). The gene discussed is VEGFD; the disease is tuberous sclerosis.