Fourth branchial pouch anomaly presenting as a neonatal neck lump.

A 1-week-old female infant presented with a transilluminating neck lump that increased in size with crying. The presumptive diagnosis was lymphatic malformation, but imaging raised the possibility of an abscess or necrotic tumour. A biopsy revealed a likely developmental cyst with local inflammatory change. Microlaryngoscopy revealed a fourth branchial pouch sinus, which was cauterised. The sinus and neck lump resolved without need for further treatment. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.