The term branchia is a Greek word meaning gill and is defined usually in the context of respiratory organs of water-living animals [2]. A branchial cleft cyst usually arises during embryogenesis if a portion of the cleft fails to involute completely. This entrapped remnant becomes an epithelium-lined cyst located in the lateral aspect of the neck [4, 6].
The differential diagnosis for neck masses is broad and includes branchial cleft cyst, thyroglossal duct cyst, dermoid cyst, hemangioma, neurogenic tumor, lymphoma, lipoma, and most commonly inflammatory neck masses [3]. Branchial anomalies account for approximately 30% of all congenital neck masses and usually present as cysts, sinuses or fistulae [5].
Although congenital, they may not present clinically until early adulthood. They are rarely bilateral and may cluster in families [1]. Ultrasound, computed tomography, or MRI will delineate the cystic nature of the mass [3]. Branchial cysts are smooth, round, and non-tender. They are located generally at the anteromedial border of the sternocleidomastoid muscle between the muscle and overlying skin, not associated with cervical vascular structures and may become inflamed, infected, and have associated purulent discharge if a sinus tract is present [5]. Dermoids are located adjacent or within a thyroid lobe and neurogenic tumors are paraspinal [7].
A fine-needle aspiration may be necessary to distinguish a branchial cleft cyst from malignancy or to guide antibiotic therapy for infected cysts [5]. Typical ultrasound characteristics include a well-defined cystic mass with an enhancing rim and lack of Doppler flow, distinguishing a branchial cleft cyst from hemangioma, lymphoma, or other rare branchiogenic carcinoma [7]. Surgical excision is the definitive treatment [3].
Unfortunately, follow-up in this case to determine definitive diagnosis was not possible. However, we are confident that given the location of the mass and its benign ultrasonographic characteristics, in addition to the patient’s previous fine-needle aspiration suggesting such, the most likely diagnosis was a branchial cleft cyst. Importantly, several case reports [8–10] would argue that without this prior knowledge of a benign fine-needle aspiration, it would be unwise to assume, based solely upon ultrasound findings, that this not a cancerous lesion.