Congenital anomalies that usually arise from second cleft/pouch, with remnants of the third and fourth pouch are rare.
M/C congenital cause of neck masses.
Classification
M/C second arch branchial cysts (90% cases)
Bailey classification of second branchial cleft cysts:
Type I (M/superficial): Anterior margin of sternocleidomastoid muscle, deep to platysma muscle
Type II (M/C): Along anterior margin of sternocleidomastoid muscle, lateral to carotid space and posterior to submandibular gland (classic location)
Type III: Extends medially b/w carotid bifurcation and lateral wall of pharynx
Type IV: Lies in pharyngeal mucosal space; lined with columnar epithelium
Schematic representation of the possible locations of second branchial cleft cysts (blue line) from the supraclavicular region to the oropharyngeal mucosa | Valentino, M., Quiligotti, C., & Carone, L. (2013). Branchial cleft cyst. Journal of ultrasound, 16(1), 17–20. doi:10.1007/s40477-013-0004-2
Pathophysiology
Incomplete involution of branchial cleft structures between the second and sixth–seventh weeks of fetal life.
Frontal schematic representation of a 5-mm human embryo at the fifth week of gestation. Sagittal sections taken through the branchial apparatus demonstrate the anatomic relationship of external clefts and internal pouches as well as the derivation of important head and neck structures. The sixth arch is very small and not visualised as a separate, discrete structure from pouch 4/5 in fig. | Waldhausen J (2006) Branchial cleft and arch anomalies in children. Seminars in Pediatric Surgery
Clinical features
Although the masses are congenital, they are usually identified only in the second to fourth decades of life, when they become enlarged secondary to infection or rupture.
Unilateral, slow-growing, fluctuant soft-tissue swelling that typically appears in the lateral aspect of the neck.
Clinical image showing swelling in the neck | Chavan, S., Deshmukh, R., Karande, P., & Ingale, Y. (2014). Branchial cleft cyst: A case report and review of literature. Journal of oral and maxillofacial pathology : JOMFP, 18(1), 150. doi:10.4103/0973-029X.131950
(a) Solitary globular swelling in the posterolateral aspect of neck along the sternocleidomastoid muscle and in the paramedian region of the neck. (b) Solitary globular swelling in the paramedian region of the neck | Panchbhai, A. S., & Choudhary, M. S. (2012). Branchial cleft cyst at an unusual location: a rare case with a brief review. Dento maxillo facial radiology, 41(8), 696–702. doi:10.1259/dmfr/59515421
Diagnosis
CT/MRI scan:
Fluid-filled cyst outlining its size and anatomic relationships
Characteristic thick wall of a branchial cyst
Contrast-enhanced computed tomography scan, taken at the level of the thyroid cartilage. A large, well-defined, non-enhancing water attenuation mass is noticeable at the axial, coronal, and sagittal planes, deep to the left sternocleidomastoid muscle | Bagchi, A., Hira, P., Mittal, K., Priyamvara, A., & Dey, A. K. (2018). Branchial cleft cysts: a pictorial review. Polish journal of radiology, 83, e204–e209. doi:10.5114/pjr.2018.76278
Differential diagnosis
Lymphadenopathy
Hemangioma
Carotid body tumour
Cystic hygroma
Ectopic thyroid/salivary tissue
Vascular neoplasm/malformation
Management
Surgical excision:
A) clinical image showing a mass of the upper-left neck; B) axial T1-weighted MRI shows a well-defined hypointense mass that was confined to the left aspect of the neck (arrow); C) the mass (arrow) was hyper-intense on T2-weighted sequences (Axial T2-weighted MRI); D) peroperative view; E) the excised mass was an encapsulated cystic structure | Sellami, M., & Ghorbel, A. (2017). Branchial cleft cyst: a case report. The Pan African medical journal, 26, 102. doi:10.11604/pamj.2017.26.102.11895
