What are the types of auricular sinuses?

Types of Auricular Sinuses

Auricular sinuses can be classified into different types based on their anatomical location, with the most common being preauricular sinuses, but also include variant types such as postauricular sinuses and comprehensive types that involve multiple locations around the ear. 1, 2

Primary Classification of Auricular Sinuses

1. Preauricular Sinuses (Classical Type)

• Most commonly present as small openings adjacent to the external ear near the anterior margin of the ascending limb of the helix 1
• Usually unilateral but can be bilateral in 25-50% of cases, with bilateral presentation increasing the likelihood of inheritance 1
• Show an incomplete autosomal dominant inheritance pattern with reduced penetrance and variable expression when inherited 1

2. Variant Types of Auricular Sinuses

Based on the location of the sinus opening, variant types can be classified into:

• Type 1 Variant (Postauricular Sinus):

  • Pits located posterior to an imaginary vertical line tangent to the external auditory canal 3
  • Sinuses penetrate the cartilage and cause postauricular swelling or skin defects 3
  • Account for approximately 62.5% of variant cases requiring surgical intervention 3

• Type 2 Variant:

  • Sinuses that adhere to the cartilage and cause preauricular or auricular swelling 3
  • Less common than Type 1, accounting for about 12.5% of variant cases 3

• Type 3 Variant:

  • Pits located on the lobule of the ear 4
  • Rarest form of variant auricular sinuses 4

• Comprehensive Group:

  • Patients with pits both anterior and posterior to the imaginary vertical line 3
  • Represent approximately 25% of variant cases requiring treatment 3

Alternative Classification Based on Fistula Pit Location

Another classification system divides variant preauricular sinuses into three types 4:

• Type 1: Pits located on the ascending helix crus (most common variant)

  • Fistular tracts often penetrate the cartilage of the helix crus 4
  • Swelling and discharge may be located at the ascending helix crus, cavum concha, or posterior to the auricle 4

• Type 2: Pits located on the external auditory canal

  • Fistular tracts typically adjacent to the cartilage of the ascending helix and tragus 4

• Type 3: Pits located on the lobule (least common variant) 4

Clinical Significance and Management

• Auricular sinuses may be asymptomatic or become infected, most commonly with gram-positive bacteria 1
• When infected, they require antibiotic treatment and possibly surgical excision 1, 2
• Recurrence rates after surgery range from 9% to 42%, with meticulous excision by an experienced surgeon minimizing this risk 1
• Auricular sinuses can be associated with other congenital anomalies in 3-10% of cases, primarily with deafness and branchio-oto-renal (BOR) syndrome 1
• When other congenital anomalies coexist with these sinuses, auditory testing and renal ultrasound should be considered 1

Surgical Considerations

• Wide local excision of the sinus is preferred over simple sinectomy for definitive treatment 2
• For variant types, especially those that penetrate cartilage, a dual approach with accurate fistula tracing and proper cartilage removal is recommended 3
• Meticulous dissection and complete removal of fistula tissue are critical to avoid postoperative recurrence 4