3-Day-Old Neonate With Prominent Airway Deviation Due to Large Cervicothoracic Thymic Cyst

Abstract

INTRODUCTION: Cervico-thoracic mass in the pediatric population is uncommon and has a broad differential diagnosis. We present a case of an extremely large cervico-thoracic mass causing airway obstruction in a 3-day-old otherwise healthy male infant. CASE PRESENTATION: Our patient was a 3-day-old male infant born to a 17-year-old G1P1 female. Pregnancy was uncomplicated with routine prenatal care. Prenatal labs were notable for negative Group B streptococcus, hepatitis B, rubella and a nonreactive VDRL (Venereal Disease Research Laboratory.) He was born by vaginal delivery at 39 and 5/7 weeks gestation with APGARS of 9 and 9 at 1 and 5 minutes. Initial course in the newborn nursery was unremarkable with no signs of respiratory distress or feeding difficulty. He was discharged home after 2 days. Over the following 24 hours the patient developed difficulty feeding with increasing lethargy and intermittent apnea at home and was brought to the local emergency room for evaluation. On exam, he was found to have a large, soft neck mass with biphasic stridor. A CT scan noted a cystic lesion extending from the anterior mediastinum to the pre-vertebral space and superiorly into the hypopharyngeal region with a homogenous fluid layer. The mass caused prominent rightward and posterior laryngeal and tracheal deviation. Given this finding, he was transported to our institution for evaluation by pediatric otolaryngology. On arrival, he was on nasal cannula oxygen but continued to have intermittent desaturations, more prominent with agitation. Following evaluation by pediatric otolaryngology, he was taken to the operating room for mass resection. Airway control was obtained through awake intubation using rigid bronchoscopy after failed direct laryngoscopy. During resection, the lesion was noted to extend from the pyriform sinus and contained foul smelling, purulent fluid. Tissue pathology revealed a thymic cyst with components of thyroid and parathyroid tissue. The fluid grew multiple organisms including Viridans streptococci, Haemophilus parainfluenzae, and Streptococcus anginosus, consistent with oral flora. Post-operatively, he developed hypocalcaemia responsive to vitamin D and calcium supplementation, which was determined to be secondary to parathyroid tissue removal. Evaluation for 22q.11 deletion by FISH (fluorescent in situ hybridization) was negative. The patient recovered from his surgery without complications and was discharged from the hospital on day of life 13. DISCUSSIONS: Differential diagnosis of cervico-thoracic masses includes congenital lesions, inflammatory lesions, traumatic lesions, and tumors. Congenital lesions are most frequent in the pediatric population with lymphangioma being most common. Congenital thymic cysts compose less than 1 percent of pediatric cervico-thoracic masses. Congenital thymic cysts arise from the anomalous development of the thymopharyngeal duct. The cyst occasionally connects to the pyriform sinus. In the only reported case in the literature, a 6-year-old presented with neck swelling and pain. Similar to our patient, airway control was a significant issue given the prominence of airway compression. Although final diagnosis in our patient was by pathology, he had features suggestive of a thymic cyst in the homogenous appearance of the fluid with an air fluid level. Nevertheless, it was important to work up immunologic and genetic etiologies given the early appearance of an infected, midline mass. CONCLUSION: The differential diagnosis for cervico-thoracic lesions is broad. In addition to diagnosis, clinicians must carefully regard the airway impact of such masses. Clinical features and radiographic findings assist with diagnosis, but pathology may be required.