Abnormal Fetal Cystic Left Neck Mass.

Abstract

An abnormal fetal cystic left neck mass was found on ultrasonography at 18 weeks gestation in a young woman. Fetal magnetic resonance imaging (MRI) demonstrated a large cystic anterior neck mass (Figure, A, sagittal view, and Figure, B, axial view, on T2-weighted half-Fourier acquired single turbo spin-echo [HASTE] MRI). The tracheoesophageal displacement index (TEDI) was found to be 24 mm. The neonate did well at the cesarean delivery (scheduled owing to the mother’s previous cesarean delivery) and had initial Apgar scores of 7 (1 minute) and 9 (5 minutes). Subsequently, the infant was intubated owing to increased difficulty with milky oral secretions and respiratory distress. Examination of the infant revealed a 5-cm, soft, fluctuant, and mobile neck mass that caused the head to deviate to the right with no cutaneous involvement. On day 2 of life, the mass had an air-fluid level and was markedly hyperintense on axial T2-weighted MRI with fat saturation (Figure, C). It appeared to be predominantly in the retropharyngeal space, anterior to the left carotid artery, and extended to abut themedial aspect of the right carotid sheath.Onday8of life, direct laryngoscopydemonstratedbulging in the left lateralpharyngealand retropharyngealwalls.Whentheneckmasswascompressed,air and fluid escaped froma communicating sinus lateral to the arytenoids in the left pyriform sinus (Figure, D). The mass was excised. A tract was isolated and ligated at the pyriform sinus, deep to the left thyroid lobe. The thyroid lobe was uninvolved. The patient was extubated on day 9 of life and had no problems breathing. What is your diagnosis? 80 mm 80 mm A B