Head and Neck Imaging

preauricular sinus

The auricle develops from six mesenchymal proliferations surrounding the first pharyngeal cleft. These swellings fuse and gradually form the definitive auricle. As this fusion is a rather complicated process, developmental abnormalites may arise. A sinus results when one of the sulci between the auricular hillocks incompletely disappears. A preauricular sinus is a relatively common congenital abnormality. It consists of a blind-ending opening in the external ear , often located at or near the anterior crus of the helix. The diagnosis is made clinically. Most of these sinuses remain asymptomatic, but repeat infection may cause chronic discharge, repeated abscess formation and scarring, making surgical excision of the sinus and its possible ramifications necessary.
Preoperative visualisation of the extent of the lesion may be helpful to prevent incomplete resection. Usually, injection of the sinus tract with contrast medium is not succesfull, as the lumen is often blocked by epithelial debris. Forced injection of methylene blue, followed by surgery a few days later has also been suggested. A non-invasive method is high-resolution ultrasound, allowing to visualize the sinus, its branches, and any associated cystic component in the subcutaneous tissues; also the relationship of the lesion to the auricular cartilage and parotid gland can be demonstrated.

RH