Branchial cleft cysts are congenital epithelial cysts that typically occur laterally in the neck, often anterior to the sternocleidomastoid muscle, and lateral to the thyroid gland. The second branchial cleft cyst is the most common type and is found in the lateral neck region.

Medial (B) would be more consistent with thyroglossal duct cysts.

Anterior (C) or posterior (D) do not specifically describe branchial cyst location relative to the thyroid.

Reference Extracts:

Som PM, Curtin HD. Head and Neck Imaging. 5th ed. Elsevier, 2011.

Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound. 5th ed. Elsevier, 2017.

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