Pediatric neck masses can be challenging to work-up in the pediatric emergency department (PED) because an untimely or incorrect diagnosis can lead to increased morbidity and mortality in these patients. This case is a great example of how to approach a teenager with worsening undifferentiated neck swelling in order to avoid missing critical diagnoses of inflammatory, neoplastic, and infectious origins. The case demonstrates the utility of point-of-care ultrasound (POCUS) in the PED as well as reviews key ultrasonographic details that help identify an infected branchial cleft cyst.