DEFINITION/OVERVIEW
- American Veterinary Dental College (AVDC) Nomenclature: the term “epulis” (epulides) is a general term referring to a gingival mass lesion of any type
- Classically considered as tumors of nonodontogenic origin that arise from periodontal connective tissue that do not metastasize1
- Categories of fibromatous (FE), ossifying (OE), acanthomatous epulis (AE)
- FE and OE have been grouped together as variants of a fibromatous category2
- FE compared to and deemed equivalent to human peripheral odontogenic fibroma (POF)3
- World Health Organization’s (WHO) “Histological classification of tumors of odontogenic origin of domestic animals”4 describes FE
- Primarily composed of periodontal ligament-type stroma; presence of regularly positioned stellate mesenchymal cells, smooth fibrillar collagen matrix, and regularly positioned and dilated but empty blood vessels
- Commonly observed cords of odontogenic epithelium and cell-poor collagen matrix resembling alveolar bone, cementum, or even dentin
- Benign tumors
- Recent retrospective study subdivided the WHO FE category into focal fibrous hyperplasia (FFH) and POF based on the presence of odontogenic epithelium
- FFH: inflammatory lesion, nonneoplastic; reactive lesion resulting from irritation caused by plaque and calculus
- Dense fibrous connective tissue with mature fibroblasts widely scattered
- Foci of dystrophic calcification amid cellular fibrous tissue
- Absence of odontogenic epithelium
- Strands of surface epithelium often visible within the fibrous tissue
- Superficial aspect may be ulcerated with associated inflammation
- FFH: inflammatory lesion, nonneoplastic; reactive lesion resulting from irritation caused by plaque and calculus
- Canine FE and human POF: equivalent
- Mass of cellular, fibroblastic connective tissue separated from surface epithelium by a zone of histologically normal fibrous connective tissue, often in the form of strands of interwoven within a looser connective matrix; connective tissue highly vascular
- Rests of odontogenic epithelium in the connective tissue vary in number
- Bone and collagenous matrix (osteoid, dentinoid, or cementum-like) present in variable amounts
- Mass of cellular, fibroblastic connective tissue separated from surface epithelium by a zone of histologically normal fibrous connective tissue, often in the form of strands of interwoven within a looser connective matrix; connective tissue highly vascular
- Primarily composed of periodontal ligament-type stroma; presence of regularly positioned stellate mesenchymal cells, smooth fibrillar collagen matrix, and regularly positioned and dilated but empty blood vessels
- Acanthomatous lesions are more distinct: termed either AE or canine (peripheral) acanthomatous ameloblastoma (CAA)
- Consists of island and cords of squamous epithelium that have invaded irregularly through a connective tissue stroma
- Basal cells arranged in palisades, vacuolated cytoplasm with reverse polarization of the nuclei and surround regularly arranged sheets of squamous epithelium
- No precise human equivalent
- AE/CAA has a clear clinicopathologic, morphological and biological differences from other categories
- Characteristic aggressive infiltrative growth of epithelial cell component in spite of minimal cell atypia and few mitotic figures
- Consists of island and cords of squamous epithelium that have invaded irregularly through a connective tissue stroma
ETIOLOGY/PATHOPHYSIOLOGY
- It has been suggested that the FE category develop in response to chronic inflammation/irritation
- Acanthomatous lesions show extremely high and rapid recurrence with a poor prognosis
SIGNALMENT/HISTORY
- Dogs: fourth most common oral mass
- Cats: rare
- Most common in brachycephalic breeds
- Boxers have a higher incidence of FE/fibrous changes (Fig. 37-1)
- Fiani retrospective study (see “Suggested Reading”)
- CAA: 45% (higher than other studies, but possibly based on more referral cases)
- Rostral mandible most common site (mandibular site-to-maxillary site ratio: 2.3 to 1)
- Mean: 8.8 years
- Golden retriever, Akita, cocker spaniels, shelties
- Rostral mandible most common site (mandibular site-to-maxillary site ratio: 2.3 to 1)
- POF: 31%
- Rostral maxilla (maxillary-to-mandible site ratio: 1.7 to 1)
- Male-to-female ratio (1.8 to 1)
- Mean: 8.5 years
- Rostral maxilla (maxillary-to-mandible site ratio: 1.7 to 1)
- FFH: 16% (lower than other studies)
- Rostral mandible
- Mean: 9.0 years
- Rostral mandible
- CAA: 45% (higher than other studies, but possibly based on more referral cases)
- History often minimal: incidental finding detected on routine physical examination
- If severe (AE, CAA): excessive salivation, halitosis, dysphagia, bloody oral discharge, weight loss
Figure 37-1 Fibrous epulis between right mandibular fourth premolar and first molar.
(Image courtesy of Thomas Klein)
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
