Lymphatic malformations (LMs) are congenital vascular anomalies occurring in ~1 in 4,000 births, with macrocystic variants posing significant clinical challenges. Neonatal pneumothorax, affecting 0.1–1% of live births, is rarely associated with LMs. Differentiating LM from Klippel-Trénaunay Syndrome (KTS) is crucial due to its distinct vascular risks, including deep vein thrombosis and pulmonary embolism.