Peripheral Odontogenic Fibroma (POF)

Peripheral Odontogenic Fibroma (POF) is a very common oral tumor in dogs. POF was previously known as a type of epulis, with “epulis” being an outdated umbrella term for a gingival (gum) mass. These tumors arise from the ligament which holds the tooth into the socket. They are slow growing and non-metastatic (they don’t spread to other places in the body) and are treated with surgical removal.

Quick Facts about POF:

• Starts as a visible gingival (gum) growth within the mouth, usually near the gumline and closely associated with a tooth.
• Often has a smooth, pink, expansive appearance, but can be cauliflower-like as well.
• The most common location is the front of the upper jaw (rostral maxilla), with the second most common being the back of the lower jaw (caudal mandible).
• Occurs at all ages, though usually it is seen in dogs over 3 years of age. In one study, the mean age reported was 8.5 years.
• Can be solitary (one growth) or multifocal (multiple growths), with the latter being common in Boxer and “Bully-type” breeds.
• There are no known reports of metastasis (spread to other parts of the body).
• Treatment of choice is surgical removal of the growth and the associated tooth/teeth and underlying bone.
• Virtually no recurrence with appropriate clean surgical margins.
• Can occur in cats but is very rare.
• Appropriate imaging, such as cone beam CT scan or intraoral radiography, can help to gauge the extent of damage and thus the appropriate surgical approach.
• The sooner these are seen and treated, the more conservative we can be with surgery, and thus preserve as many healthy teeth as possible.

Diagnosis:

Definitive diagnosis of all masses, regardless of location, is histopathologic examination, or evaluation of a sample of the tumor under a microscope. This is true in the case of POF as well. POFs can easily be misdiagnosed as other more aggressive types of oral tumors, so examination by a pathologist that is well-versed in oral pathology is recommended when submitting these samples.

Treatment:

The appropriate treatment for POF is en bloc (“all together”) surgical excision of the tumor and associated teeth. This means that all of the tumor would be removed in one section with the closely associated bone and/or teeth. The goal in doing this is to remove all affected tissues without excessive removal of unaffected tissue. If the entire tumor is removed and no tumor cells are seen at the edges of the removal sites (clean surgical margins), recurrence is extremely unlikely. If surgical margins are not evaluated or are ‘dirty’ (tumor cells left behind), recurrence is variable.

Prognosis with no treatment:

Though POF will not spread, it will continue to grow with time. This can lead to difficulty eating, trauma to the tumor (involving pain and bleeding), oral pain, and tooth loss.

Conclusion:

POF is a common benign oral tumor in dogs. It is considered highly treatable, with excellent outcomes and survival times following appropriate surgical intervention.

References:

Wiggs’s Veterinary Dentistry, Principles and Practice, Second Edition, 2019, Wiley Blackwell, NJ. HB Lobrise, JR Dodd, Oral and Maxillofacial Tumors, p. 143

Veterinary Oral and Maxillofacial Pathology, 2020, Wiley Blackwell, NJ. BG Murphy, CM Bell, JW Soukup, Tumor Like Proliferative Lesions of the Oral Mucosa and Jaws, p. 197-201

Computed tomographic characteristics of odontogenic neoplasms in dogs.
Vet Radiol Ultrasound. 2014 Mar-Apr;55(2):147-58.

Clinicopathologic characterization of odontogenic tumors and focal fibrous hyperplasia in dogs: 152 cases (1995-2005).
J Am Vet Med Assoc. February 2011;238(4):495-500.
Nadine Fiani 1, Frank J M Verstraete, Philip H Kass, Darren P Cox

Diagnostic imaging in veterinary dental practice. Peripheral odontogenic fibroma (POF).
J Am Vet Med Assoc. December 2013;243(11):1541-3.
Diane S Carle 1, Bonnie H Shope