What is the diagnosis and treatment of brachial cleft cysts, including imaging and management?

Branchial Cleft Cysts: Ultrasound Appearance, Workup, and Treatment

Ultrasound Appearance

Branchial cleft cysts appear on ultrasound as smooth, well-defined, anechoic or hypoechoic cystic masses located in the lateral neck, typically along the anterior border of the sternocleidomastoid muscle at the junction of its upper third and lower two-thirds. 1, 2, 3

• The cysts present as resilient, smooth tumors that may contain internal debris if infected 1
• When infected, imaging shows enhanced wall thickening, perilesional inflammation, and internal debris 4
• Ultrasound is useful for initial evaluation but should be complemented with CT or MRI for complete characterization 1, 2

Diagnostic Workup

Fine needle aspiration cytology (FNAC) should be performed as the first-line diagnostic procedure for any lateral neck mass in adults, including suspected branchial cleft cysts. 5, 2, 6

Imaging Protocol

• CT with IV contrast is the preferred initial cross-sectional imaging for suspected branchial cleft cysts, particularly when infection is suspected 4
• MRI provides superior soft tissue characterization if malignancy needs exclusion 4
• Both CT and MRI help identify fistulous tracts, which is critical for surgical planning 1, 2

FNAC Performance

• FNAC demonstrates 100% sensitivity, 100% positive predictive value, and 100% accuracy for diagnosing branchial cleft cysts 6
• If initial FNAC is non-diagnostic, repeat image-guided FNA or core needle biopsy should be performed before proceeding to excisional biopsy 5
• Ultrasound guidance increases diagnostic yield by targeting solid components 5

Critical Differential Considerations

• Age >40 years significantly increases malignancy risk (up to 80% in cystic neck masses), requiring tissue diagnosis to exclude malignancy 5
• Intraparotid or cervical lymphadenopathy may represent metastatic disease and requires careful head and neck skin examination 5

Treatment

Complete surgical excision is the only effective treatment for branchial cleft cysts, and should be performed after any acute infection has resolved. 1, 2, 6

Acute Management (If Infected)

• Initiate broad-spectrum antibiotics covering oral flora and skin organisms 4
• Consider aspiration if abscess formation is present on imaging 4
• Defer definitive surgery until infection resolves to reduce recurrence risk 1, 3

Definitive Surgical Management

• Total surgical excision under general anesthesia is the treatment of choice 2, 6
• Incomplete removal results in recurrence; complete excision prevents this complication 1, 2, 6
• The surgical approach must ensure safe and complete cyst removal to avoid intraoperative complications 2
• All procedures should be performed on the deep face of the platysma muscle 7

Common Pitfalls to Avoid

• Never leave residual cyst tissue, as this leads to recurrence 1, 2
• Failure to identify and excise associated fistulous tracts increases recurrence risk 1, 2
• Operating during active infection increases surgical complications and recurrence 1, 3
• Lack of treatment puts patients at risk for repeated infections and rare complications like internal jugular vein thrombosis 3

Expected Outcomes

• With complete excision, no recurrences occur during long-term follow-up (1-7 years) 2, 6
• Postoperative recovery is typically smooth without complications when proper technique is used 6, 7