A Rare Cause of Neck Lump in an Infant.

A 5 month old girl presented to the Paediatric Emergency Department with a rapidly growing neck mass over 24 hours. She was systemically well and otherwise asymptomatic. On examination she had a mobile, soft and non-tender 5 cm x 5 cm neck mass. Blood tests were unremarkable with normal inflammatory markers. Point of Care Ultrasound (POCUS) was done which showed a solid left sided neck mass with increased vascularity but no evidence of collection or abscess. Given the atypical presentation and rapid growth the patient was commenced on empirical antibiotics and was discussed with both tertiary ENT and Oncology teams. An MRI was performed which was indeterminate. Biopsy of the neck mass was positive for Ewing Sarcoma. This is a rare case of Ewing Sarcoma in an infant. POCUS can be used to rule out common pathology and abnormal lymph nodes, aiding in ongoing investigation and management in neck lumps.