Study proposes new name for a common canine gingival lesion
Bottom line
Fibromatous epulis of periodontal ligament origin, also called peripheral odontogenic fibroma, may be better understood as a reactive hyperplastic lesion rather than a true neoplasm, according to a new Veterinary Pathology study by Cynthia M. Bell, Brian G. Murphy, and Jason W. Soukup. In 100 surgically excised canine lesions evaluated histologically, the authors found evidence supporting a hyperplastic pathogenesis and proposed a unifying new name: fibromatous hyperplasia of the gingival ligament. The proposal aims to resolve long-running confusion around dual terminology that has persisted in veterinary dentistry and pathology for years. (wsava.org)
Why it matters: For veterinary professionals, the naming shift could do more than tidy up pathology reports. Peripheral odontogenic fibroma/fibromatous epulis is one of the most commonly diagnosed benign oral lesions in dogs, and consistent nomenclature may improve communication among general practitioners, dentists, surgeons, and pathologists. It also may sharpen expectations around biologic behavior and treatment planning, especially as the field is already refining how it classifies related gingival masses, including hypercellular peripheral odontogenic fibromas and newly described gingival mucoperiosteal fibromas. Recent literature has emphasized that some lesions with atypical histologic features still behave benignly after excision, underscoring the clinical value of precise classification. (pubmed.ncbi.nlm.nih.gov)
What to watch: Watch for whether pathologists, dental specialists, and future guidelines adopt “fibromatous hyperplasia of the gingival ligament” in place of FEPLO/POF. (journals.sagepub.com)
Key facts
- Study type
- Veterinary Pathology study
- Authors
- Cynthia M. Bell, Brian G. Murphy, and Jason W. Soukup
- Sample size
- 100 surgically excised canine lesions
- Finding
- Histologic evidence supported a hyperplastic, not neoplastic, origin
- Current names
- Fibromatous epulis of periodontal ligament origin, also called peripheral odontogenic fibroma
- Proposed name
- Fibromatous hyperplasia of the gingival ligament
- Clinical context
- One of the most commonly diagnosed benign oral lesions in dogs
- Purpose
- To resolve long-running dual terminology in veterinary dentistry and pathology
A common canine gingival lesion may be getting a new identity. In a new study in Veterinary Pathology, Cynthia M. Bell, Brian G. Murphy, and Jason W. Soukup report histomorphologic evidence that fibromatous epulis of periodontal ligament origin, also known as peripheral odontogenic fibroma, is better explained by hyperplastic pathogenesis. Based on that review, they propose a single unifying term: fibromatous hyperplasia of the gingival ligament. (wsava.org)
The recommendation lands in an area of veterinary oral pathology that has long been crowded with overlapping labels. “Epulis” has historically been used as a clinical catchall for gingival masses in dogs, but efforts over decades have tried to separate reactive lesions from odontogenic tumors and other proliferative conditions. A 2014 historical review by Soukup and Bell highlighted that the nomenclature around odontogenic tumors has been unsettled for years, helping explain why both FEPLO and POF remain in circulation. (journals.sagepub.com)
The new study examined 100 canine FEPLO/POF lesions that had been surgically excised en bloc, with the goal of clarifying histogenesis and pathogenesis. While the full paper was not freely accessible in the search results, the abstract provided in your source material reports that the lesions were assessed histologically for their relationship to surrounding structures, and the authors concluded the findings support a hyperplastic, not neoplastic, origin. That distinction is what underpins the proposed terminology change. Because the lesion is benign and common, a unifying name could have outsized practical value in everyday diagnostic workups. (wsava.org)
That proposal also fits with a broader trend in the literature toward finer-grained classification of canine oral fibrous lesions. In 2024, a study of 20 dogs described non-invasive and locally invasive hypercellular peripheral odontogenic fibroma as a distinct subset after some cases had raised concern for odontogenic sarcoma; despite worrisome histologic features, no recurrences were reported after excision. Another retrospective review of 54 hypercellular canine POFs likewise found they did not appear to carry worse survival, recurrence, or metastatic risk than typical POFs, suggesting they can be managed similarly in practice. (journals.sagepub.com)
The same authorship network has also been active in defining other poorly categorized oral fibrous lesions. In 2025, Bell and colleagues described gingival mucoperiosteal fibroma in 27 dogs as a benign fibrous oral mass lacking odontogenic tissue, with no recurrence seen at follow-up after surgical resection. Taken together, these papers suggest veterinary oral pathology is moving toward a more behavior-based and tissue-of-origin-based framework, rather than relying on older umbrella terms that may blur important distinctions. (journals.sagepub.com)
Why it matters: For veterinarians, dentists, and pathologists, the main value of this study may be clarity. FEPLO/POF is not a rare edge case; biopsy-based retrospective data from Portugal found FEPLO/POF accounted for 208 of 256 benign neoplasms in canine oral lesions submitted over an eight-year period, and current WSAVA dental guideline materials still describe POF/FEPLO as a common mesenchymal odontogenic oral tumor in dogs. If the field increasingly accepts a hyperplastic model and the new term, it could influence report wording, case discussions, teaching materials, and possibly how clinicians frame prognosis and surgery with pet parents. (pubmed.ncbi.nlm.nih.gov)
There’s also a communication benefit. General practitioners often see these lesions first, while definitive diagnosis depends on histopathology and, in some cases, imaging and dental specialty input. A single preferred term could reduce confusion between reactive gingival overgrowths, odontogenic tumors, and other benign fibrous masses. That may be especially useful as newer entities, such as gingival mucoperiosteal fibroma and hypercellular POF, continue to enter the diagnostic vocabulary. (journals.sagepub.com)
What to watch: The next question is adoption. Watch for whether future editions of oral pathology references, specialty education materials, conference presentations, and guideline documents begin replacing FEPLO/POF with “fibromatous hyperplasia of the gingival ligament,” or whether the older dual terminology persists during a transition period. A 2026 veterinary oral pathology text listing “fibromatous hyperplasia of the gingival ligament” suggests that shift may already be underway, but broader uptake will likely depend on how quickly diagnostic labs and specialists align around the change. (distribuzione.evsrl.it)