Fetal therapy using rapamycin for a rapidly enlarging, obstructive, cervical lymphatic malformation: a case report.

WHAT'S ALREADY KNOWN ABOUT THIS TOPIC?: Fetal lymphatic malformations (LMs) can be detected on prenatal ultrasound and until recently, therapeutic options were limited. Recently the mammalian target of rapamycin inhibitor rapamycin has emerged as a safe, effective therapy for children with LMs and multiple studies have demonstrated improved efficacy if started early. WHAT DOES THIS STUDY ADD?: We report the first in-utero therapy with rapamycin for a rapidly enlarging, obstructive, fetal cervical LM. Fetal therapy with rapamycin was safe and effective in managing this severe malformation, despite rapamycin being started only in the last 6.5 weeks of pregnancy. We speculate that had rapamycin been commenced earlier, the reduction in mass size might have been even greater.