IntroductionOesophageal duplication cyst (EDC) is a rare congenital anomaly representing, after neuronal tumours, the second most common cause of posterior mass in children, with a prevalence of approximately 1/22,500 live births. Cervical cysts are very rare, and their antenatal detection is fairly uncommon.MethodsWe report the case of an isolated large mediastinal and cervical tubular EDC diagnosed prenatally in the third trimester.ResultsAfter birth, the baby became symptomatic developing respiratory distress due to the enlargement of the cyst and she underwent excision of the mass. The post‐operative evolution was very good.ConclusionOur purpose was to raise awareness of the ultrasonographic features of this condition, thus improving the rate of prenatal diagnosis and offering the parents a proper counselling regarding the prognosis and the need for a further multidisciplinary approach after birth.