There is a nice article in the journal Archives of Otolaryngology-- Head Neck Surgery (first reference below) which examines the relationship of preauricular sinuses to auricular cartilage. (photo credit)
Preauricular sinuses are a congenital malformation of the preauricular soft tissues. They can be both sporadic and inherited. They are bilateral in approximately 25% to 50% of patients. When bilateral, the sinuses are more likely to be inherited in an autosomal dominant pattern with reduced penetrance and variable expression.
Although the true prevalence is not well established, preauricular sinuses are thought to occur most commonly in black populations. The incidence of preauricular sinuses has been estimated to be 0.1% to 0.9% in Europe and the United States.
Preauricular sinuses are the most common variant of all the periauricular cysts, fistulas, and sinuses. The cutaneous pit of the preauricular pit is most often located on or near the ascending limb of the helical rim but can also open along the superior posterior margin of the helix as well as the tragus.
While both cutaneous opening and fistulous tracts are classically located anterior to the external auditory canal, a reported variant form has its opening behind an imaginary vertical line drawn at the posterior most aspect of the tragus and the posterior aspect of the ascending limb of the helix. This variant typically presents with postauricular swelling and requires both postauricular and preauricular incisions for its removal. (photo credit)
The article takes you through a review of the embryology (photo credit)
Classically, the surgical approach consists of a simple sinectomy with an elliptical island of skin removed around the opening of the sinus and excision of the epithelial sinus tract. Various authors have advocated the use of either methylene blue or gentle probing of the tract to carefully delineate the tract. However, neither approach guarantees full removal of the tracts: reported recurrence rates are quite high, typically near 20%…………..
Because the present study is not a randomized controlled trial, our findings cannot be used to determine whether excision of cartilage or perichondrium prevents recurrence of preauricular sinuses. …… In over 50% of the specimens reviewed, the sinocartilaginous distance was less than 0.5 mm, and in nearly all of these cases, the epithelial tract was in continuity with stromal tissue histologically indistinguishable from the perichondrium.
The removal of a small piece of cartilage or perichondrium does not produce a visible cosmetic deformity or add any significant morbidity. Therefore, the routine removal of a small portion of perichondrium and/or auricular cartilage along with the sinus tract may yield a more thorough excision and help to prevent recurrence.
The Histologic Relationship of Preauricular Sinuses to Auricular Cartilage; Arch Otolaryngol Head Neck Surg. 2009;135(12):1262-1265; Brian Dunham, MD; Martha Guttenberg, MD; Wynne Morrison, MD; Lawrence Tom, MD
Preauricular Sinuses; eMedicine Article, January 8, 2010; Noah Scheinfeld, MD, Valerie Nozad, DO, and Jeffrey Weinberg, MD
Surgical Treatment of Recurring Preauricular Sinus: Supra-auricular Approach; Acta Otorhinolaryngol Ital. 2008 December; 28(6): 302–305; G Leopardi, G Chiarella, S Conti, and E Cassandro
The Preauricular Sinus: A Review of Its Aetiology, Clinical Presentation and Management; International Journal of Pediatric Otorhinolaryngology (2005) 69, 1469—1474; T. Tan, H. Constantinides, T.E. Mitchell