Accessory Tragus: A Rare Congenital Anomaly in a Dog.

Area of Science:

• Veterinary Dermatology
• Congenital Malformations
• Comparative Pathology

Background:

• Accessory tragus is a congenital malformation of the external ear in humans, presenting as a benign cutaneous mass.
• These masses occur along the first branchial arch's migratory path, typically between the ear tragus and mouth angle.
• In humans, accessory tragus is often associated with other congenital anomalies and syndromes.

Purpose of the Study:

• To report the first documented case of accessory tragus in a non-human species.
• To highlight the potential for this condition to indicate other congenital defects in animals.
• To inform surgical excision practices for this lesion.

Main Methods:

• A six-month-old male American pit bull terrier presented with a congenital, haired, pedunculated cutaneous mass on the left maxillary region.
• Histopathological examination of the mass was performed.
• A retrospective review of diagnostic records from 2008-2018 was conducted.

Main Results:

• The mass was diagnosed as an accessory tragus, characterized as a polypoid extension of haired skin with a core of adipose tissue and elastic cartilage.
• This represents the first reported instance of accessory tragus in a canine.
• No other similar cases were identified in a decade-long retrospective review.

Conclusions:

• Accessory tragus, previously only documented in humans, has now been identified in a dog.
• Identifying this condition in animals may prompt the investigation of concurrent congenital abnormalities.
• Awareness of this lesion can guide appropriate surgical management to prevent complications like chondrodermatitis.