13-month-old female with left neck swelling.

Abstract

A 13-month-old female was brought to the emergency department by her mother for 2 days of left neck swelling (Figure 1). Per her mother, the patient had developed progressive swelling and erythema after scratching the area over the last week. Otherwise, she was asymptomatic with normal vital signs. Before the patient's swelling, there had been a “dimple” at the area since birth. A point-of-care ultrasound was performed, demonstrating a 2.1 × 2.3 × 2.1 cm cystic and heterogeneous structure (Figure 2). Infected Branchial Cleft Cyst. Branchial cleft anomalies are remnants of branchial cleft mucosa during embryogenesis.1, 2 Incomplete involution of the mucosa create vestigial cysts, sinuses, and/or fistulas. There is a predilection for branchial cleft anomalies on the left side, more common in females, and second branchial cleft anomalies are the most common.3 Branchial cleft cysts present as a painless soft tissue mass around the anterolateral neck, along the anterior sternocleidomastoid muscle. If infected, they can become swollen and tender. Rarely, the cyst can lead to complications of airway compromise and glossopharyngeal and hypoglossal nerve compression due to mass effect.4 Clinical and radiological diagnostics can raise suspicion for branchial cleft cysts. Definitive diagnosis is made with cyst excision and histological examination, demonstrating a cystic cavity lined by epithelium and underlying connective tissue showing germinal centers.4 Other diagnoses to consider for pediatric superficial neck masses are lymphadenopathy, thyroglossal duct cyst, or dermoid cyst. Conservative treatment of needle aspiration, incision and drainage, and injection of sclerosant agents may be trialed, but recurrence is common.1-4 Definitive treatment is surgical excision.