Cornifying Epitheliomas in Dogs

What are cornifying epitheliomas?

Cornifying epitheliomas (also known as intracutaneous cornifying epitheliomas, infundibular keratinizing acanthomas, or keratoacanthomas) are benign skin tumors in dogs. They form when cells in the hair follicles multiply uncontrollably. These cells create keratin – a tough substance normally found in hair and nails; however, with this condition, the keratin collects within the tumor in abnormal amounts.

Cornifying epitheliomas appear as firm, nodular masses that may ulcerate (create an open sore) or may have a small hole or pore that can release a thick, cheese-like discharge. They often occur individually but can occur in multiple locations.

Some affect the nail bed and are called subungual keratoacanthomas.

What causes cornifying epitheliomas?

The exact cause of cornifying epitheliomas is not fully understood, but they are linked to abnormal keratinization processes within hair follicles. Certain breeds are predisposed, including terriers, keeshonds, Norwegian elkhounds, and German shepherds, which suggests a potential genetic component. There are rare reports of cornifying epitheliomas occurring in cats. Hormonal influences or chronic irritation may also play a role in their development.

How are cornifying epitheliomas diagnosed?

After evaluation during a physical examination, diagnosis typically involves:

• Fine Needle Aspiration (FNA): To collect and examine cell samples under a microscope (cytology).
• Histopathology: In cases where FNA results are not clear, a piece (biopsy) of the tumor provides a definitive diagnosis by analyzing tissue structure and cellular characteristics.
• Imaging: X-rays (radiographs) may be recommended.

How do cornifying epitheliomas typically progress?

• Generally slow-growing and non-aggressive.
• Rarely spread to other parts of the body (metastasize).
• Without treatment, they may become inflamed, infected, or ulcerated, leading to discomfort or secondary complications like skin infections.
• If they affect the nail bed, they may cause nail deformities and limping and can change how the bone appears on X-rays.

What are the treatments for this type of tumor?

Treatment options depend on the tumor's size, location, and the overall health of the dog. Surgery is often the treatment of choice for single masses. The risk of recurrence is low when the mass is removed entirely. Cryosurgery, a technique that uses a liquid nitrogen spray or laser ablation, may be an option for smaller, more superficial masses.

In cases where surgery isn't feasible, medications may be prescribed to manage inflammation or infection, but they do not resolve the tumor. Your veterinarian may recommend a retinoid to try to improve skin health.

Is there anything else I should know?

Your pet should not be allowed to bite, lick, or scratch the tumor, as doing so may cause bleeding, ulceration, and secondary infection. Monitor your pet’s mass closely and look for any new masses developing. Contact your veterinarian as soon as possible if you see any changes.