The Bailey classification of second branchial cleft cysts defines the anatomic location of second branchial cleft cysts in four categories, from superficial to deep. This classification was initially proposed by Bailey in 1929 2 and remains the most widely used classification system because it gives a sense of the potential locations of these lesions and helps to frame a description.
- type I: between the platysma and sternocleidomastoid muscle
- type II: between sternocleidomastoid muscle and submandibular gland, lateral to the carotid sheath
- type III: extends between the internal and external carotid arteries
- type IV: medial to the carotid sheath, in the parapharyngeal space or pharyngeal mucosal space opening into the oropharynx
Among these, type II is the most common and corresponds to the classic description of these lesions in the submandibular space 3,4. A beak, tail, or notch sign of cyst extension between the internal and external carotid arteries indicates a Bailey type III cyst 5.