2nd branchial cleft cyst
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Cystic dilatation of remnant of the 2nd branchial apparatus, typically presenting as a rounded swelling just below angle of mandible, anterior to sternocleidomastoid (although position is variable - see below). May communicated with the pharyngeal mucosa and / or skin, when it then known as a 2nd branchial cleft sinus or 2nd branchial cleft fistua respectively. The sinus / fistulla typically passes between the internal and external carotid artery.
The cyst is typically filled with mucoid material, is well circumscribed and other than presenting as a swelling is asymptomatic. If infected however, then surrounding stranding and skin changes are evident.
Focal notch of cyst wall extenting to the carotid bifurcation is 'pathognomonic' (notch sign)
Usually presents in early childhood <5 years of age, although a second peak is in the 2nd and 3rd decade.
Classification
| Type | description |
|---|---|
| I | beneath platysma, anterior to sternocleidomastoid (SCM) |
| II | immediately adjacent to internal carotid artery and adherent to internal jugular vein, (most common) |
| III | extends between internal and external carotid artery |
| IV | against pharyngeal wall and may extend superiorly to skull base. |