Preauricular Sinus
A preauricular sinus (preauricular cyst / auricular fistula), often called an "ear pit," is a common benign birth defect of the outer ear. It forms when the embryonic ear mounds (the hillocks of His) fail to fuse properly around the sixth week of pregnancy.
The fetal outer ear is built from six small tissue mounds, three from the first branchial arch and three from the second. When these mounds do not merge completely, a skin-lined tube becomes trapped, leaving a tiny opening on the skin that leads into a tract running deep into the connective tissue, right up against the ear cartilage covering.
Structure and Contents of the Sinus Tract
- Opening (punctum / pit): Usually located where the front edge of the ascending helix meets the temple, or just in front of the tragus.
- Winding tract (sinus tract network): Behind the opening lies a short or winding, branching network of skin-lined channels that runs under the skin and adheres firmly to the ear cartilage lining (perichondrium).
- Contents: The lining constantly sheds keratin and secretes sebum, which collect as a thick, chalky off-white material with a strong, characteristic odor.
How Infection Develops and Damages the Ear
A quiet preauricular sinus is usually harmless. However, if it is squeezed, or if bacteria such as Staphylococcus aureus or Pseudomonas aeruginosa enter through the opening, the tract can become blocked and form a preauricular abscess.
The destructive inflammation not only breaks down the tract but can also inflame the ear cartilage lining (perichondritis), deform the ear cartilage and leave unsightly, puckered depressed scars in front of the ear.
The hardest part of preauricular sinus surgery is that the tract has many hidden branches and clings tightly to the cartilage lining. If only the opening is cut out, or even one small branch of lining is left behind, the rate of recurrence and repeat infection can reach 20–40%.
At Haute-Derma, we follow a standardized treatment approach:
- Mapping the tract with high-frequency skin ultrasound and micro-injection of methylene blue: Every branch and its relationship to the ear cartilage lining is located precisely before any incision is made.
- Microsurgical wide excision including the perichondrium (supra-perichondrial radical excision): The entire tract, the opening and an attached strip of cartilage lining are removed without deforming the ear, significantly reducing the recurrence rate.
Histopathology and Diagnostic Ultrasound Criteria
Characteristic Microscopic Findings
Under the microscope, a preauricular sinus looks like epidermis that has folded deep into the dermis:
- Tract lining (epithelial lining): Mostly lined by keratinized stratified squamous epithelium with all its layers, including the granular layer (stratum granulosum). Deeper segments sometimes contain ciliated pseudostratified columnar epithelium.
- Skin appendages around the tract: Vellus hair follicles, sebaceous glands and sweat glands are often found in the connective tissue surrounding the tract.
- Granulomatous inflammation (with infection or abscess): Bands of acute and chronic inflammatory cells (neutrophils, plasma cells, macrophages) and foreign-body giant cells appear around ruptured segments of the tract.
High-Frequency Skin Ultrasound and Dermoscopy Criteria
- High-frequency skin ultrasound (20–50 MHz, the preoperative gold standard):
- Hypoechoic or anechoic tubular structure (tubular hypoechoic structure): Starts at the skin surface in front of the ear and runs deep toward the base of the ear cartilage.
- Length and branching (tract branching): Shows whether the tract is a single straight tube or a tree-like branching system.
- Assessing an abscess around the tract (perifistular abscess): An irregular hypoechoic area with increased Doppler blood-flow signal around its rim from inflammatory congestion.
- Relationship to the cartilage lining (perichondrial contact): Measures the distance between the base of the tract and the ear perichondrium, and how firmly it is attached.
- Dermoscopy: Shows a gray-brown or slightly red punctum ringed by mildly dilated vessels, sometimes with a drop of cloudy white material pushing out of the opening.
Clinical Features
- Location: 90% are found at the front edge of the ascending helix.
- Quiet phase: A small 1–2 mm opening that is completely painless and occasionally leaks a little foul-smelling white material.
- Inflamed or abscess phase: The skin around the opening becomes swollen, red, hot and persistently painful; pressing on it releases foul pus through the opening, or the abscess breaks down and ruptures through nearby skin.
Clinical and Histologic Differential Diagnosis Around the Ear
| Preauricular Sinus | First Branchial Cleft Cyst | Epidermoid Cyst of the Ear |
|---|---|---|
| Front edge of the ascending helix / tragus | Angle of the jaw, parotid gland, external ear canal | Earlobe, behind the ear |
| Small opening with a tract running deep toward the cartilage | Deep cyst or sinus tract at the angle of the jaw | Mobile nodule with a central punctum |
| Firmly attached to the EAR PERICHONDRIUM | Related to the parotid gland and facial nerve (CN VII) | Within the skin, not attached to cartilage |
| Keratin + sebum + vellus hairs | Serous fluid + cholesterol crystals | Concentric, onion-skin layers of keratin |
| Often familial (autosomal dominant) | Very rarely inherited | Not inherited |
Supra-Perichondrial Radical Excision Protocol at Haute-Derma
Our treatment strategy at Haute-Derma aims to remove the entire tract to prevent recurrence, while restoring the appearance of the area in front of the ear:
Controlling Inflammation and Dye-Mapping the Tract
- Managing an abscess (if present): If the patient arrives with an acute pus-filled swelling, the doctor makes a tiny incision to drain it and prescribes culture-guided systemic antibiotics for 7–10 days until the redness and swelling settle.
- Methylene blue micro-injection (chromotubation): A fine microsurgical catheter is gently passed into the opening, and a very small amount (0.1–0.2 mL) of methylene blue is injected to stain the entire lining of the tract and its side branches blue.
Microsurgical Wide Excision With Perichondrium (Supra-Perichondrial Excision)
- Small oval skin incision (elliptical incision): A fine oval incision is designed around the opening, running parallel to the natural skin creases in front of the ear.
- Dissection along the blue-stained tract: Curved microsurgical scissors are used to separate the surrounding connective tissue from the blue-stained tract.
- Removal together with the perichondrium (resection with perichondrium): Where the tract reaches the base of the ear cartilage, the doctor removes it along with the attached layer of cartilage lining (perichondrium) in one piece. This clears residual lining cells stuck to the cartilage and significantly reduces the risk of recurrence.
Filling the Defect, Exosome Injection and Cosmetic Intradermal Closure
- Irrigation and closing the cavity: The surgical field is irrigated with a dilute antibiotic solution, and the subcutaneous connective tissue is repaired with 6-0 absorbable microsurgical sutures.
- Regenerative PDRN + exosome injection: Micro-injections of salmon DNA (PDRN) and exosomes fill the small tissue gap in front of the ear and help prevent a sunken area after surgery.
- Intradermal microsuturing (subcuticular suture): The skin is closed with 7-0 cosmetic sutures so the scar stays fine and blends into the natural fold of the ear.
