First branchial cleft anomaly

General features:
Also called parotid lymphoepithelial cyst
Seen from external auditory canal through parotid gland to submandibular triangle.
5% of all branchial cleft anomalies
Common in middle aged females

Embryology: (Work classification):
Type I (ectodermal): duplication anomaly of membranous external auditory canal, parallel to external auditory canal. No skin appendages
Type II (ecto and mesoderm): involve external auditory canal and cartilaginous pinna. May have skin appendage - hair follicle, sweat gland, sebaceous glands. Common type found in parotids

Clinical features:
Present as recurrent abscesses or sinus in the parotid or at the angle of mandible
Otorrhea
Sinus tract to hyoid bone
May cause facial nerve palsy
Seen in children and adults

Location:
Intraparotid (superficial or deep lobe) or extraparotid
Classically inferior pole of parotid or mass within EAM

Management:
Complete surgical excision

Imaging:
Cystic
Within, superficial or deep to parotid gland
Variable wall thickness and enhancement
Very difficult to deifferentiate from other parotid lesions

References:
1. Koeller KK et al. Congenital Cystic Masses of the Neck: Radiologic-Pathologic Correlation. Radiographics. 1999;19:121-146
2. Miller M, Rao V, Tom B. Cystic masses of the head and neck: pitfalls in CT and MR interpretation. AJR 1992; 159:601-607