Preauricular sinuses are common congenital malformations first described by Heusinger in 1864. [1] Preauricular sinuses are frequently noted on routine physical examination as small dells adjacent to the external ear, usually at the anterior margin of the ascending limb of the helix. However, preauricular sinuses have been reported to occur along the lateral surface of the helicine crus and the superior posterior margin of the helix, the tragus, or the lobule. Anatomically, preauricular sinuses are lateral and superior to the facial nerve and the parotid gland.

Preauricular sinuses are inherited in an incomplete autosomal dominant pattern, with reduced penetrance and variable power of expression. They can arise spontaneously. The sinus may be bilateral in 25-50% of cases, and bilateral sinuses are more likely to be hereditary. [2] In unilateral cases, the left side is more commonly affected.

Also see the related article Preauricular Cysts, Pits, and Fissures.