How I approach… Gingival enlargement in the dog

Introduction – What is gingival enlargement?

The descriptive term “epulis” is regularly used in primary care practice to describe a focal enlargement of the gingiva, but it is also ambiguous. In the Greek language “epulis” means “on the gum” and although this descriptive terminology seems logical, there is a lack of clarity and consistency between practitioners on what exactly an “epulis” describes and implies, which can result in medical errors, inappropriate treatment, and confusion for clients and colleagues. In a contemporary dentistry service, I recommend that we collectively avoid using the word, and instead the term “gingival enlargement” (GE) should be encouraged to describe a focal enlargement of the gingiva in the absence of a histopathological diagnosis and absence of an inferred prognosis. A GE may therefore subsequently be identified as a benign or malignant neoplastic lesion, or a non-neoplastic, reactive tumor-like lesion of the gingiva 1.

This short article aims to demonstrate the diversity of pathology that can present as a gingival enlargement in a dog’s mouth. It will reveal the importance of obtaining a diagnosis of a GE through histopathology, and provide superficial information on treatment and prognosis for various conditions (including, where appropriate, to perform treatment and obtain a diagnosis during the same procedure). It will also offer a guide on how to perform gingivectomy and gingivoplasty in a clinical scenario where focal fibrous hyperplasia, a type of gingival hyperplasia, is suspected.

How to evaluate a GE

When evaluating a GE, it is imperative that the fundamentals of a COHAT (Complete Oral Health Assessment and Treatment) are followed. This encompasses a visual assessment; orodental charting that includes periodontal probing; diagnostic imaging [either intraoral radiographs or computed tomography (CT)]; and measurement of the GE along with a description, including the location, shape, size, texture, color, etc.

To achieve a diagnosis, an incisional biopsy is obtained from the abnormal tissue and submitted for histopathology. Obtaining large and deep incisional biopsies is important to provide the pathologist with adequate tissue to properly diagnose the lesion. A common error in primary care practice is taking superficial biopsies that do not reflect the pathology present, or have regions of necrosis, leading to misdiagnosis and inappropriate treatment. I use either a scalpel blade to take an elliptical incisional sample, or a punch biopsy of appropriate size. If indicated, the biopsy site edges should then be apposed with resorbable suture. For a pedunculated GE, I often incise the pedunculated stalk at the interface between pathology and normal gingiva. Fine-needle aspiration is commonly non-diagnostic and is not recommended.

For most patients, the clinical appearance of a GE is not pathognomonic, and a diagnosis should be obtained prior to creating a definitive treatment plan and discussion with the owner. It is important to explain the rationale of this approach to the client to ensure that the correct treatment modality is elected, an appropriate extent of surgery is performed, and proper systemic evaluation is performed (such as staging, sentinel lymph node assessment, etc.).

In some cases, there may be a recognizable pattern of GE, and it may be rational to perform both diagnostics (incisional biopsy in the form of a gingivectomy and gingivoplasty) and treatment during the same procedure. The most common example of this would be when generalized GE is identified in a mature Boxer, a breed notorious for developing gingival hyperplasia (most commonly a type known as “focal fibrous hyperplasia”). Following discussion with the owner, it may be reasonable to perform gingivectomy and gingivoplasty to both recontour the gingiva to “as close as possible to the physiologic gingiva” and to simultaneously obtain representative samples for histopathology in order to confirm the clinical suspected pathology.

Gingival hyperplasia

Gingival hyperplasia is a non-neoplastic, reactive inflammatory lesion that can vary in its appearance (Figure 1). The most common causes are plaque-induced gingivitis/periodontitis, occlusal trauma, and certain medications (most commonly cyclosporine and amlodipine) 2. The term “focal fibrous hyperplasia” is used to describe a form of gingival hyperplasia that is characterized by negligible hyperplasia of the epithelium, but rather is defined by its dense fibrous connective tissue 2.

Treatment of gingival hyperplasia includes resection (by gingivectomy and gingivoplasty) of the excess tissue and recontouring of the attached gingiva for both diagnosis and therapeutic purposes (see the following page). If occlusal trauma is stimulating gingival hyperplasia to form, resolution of the malocclusion is recommended. If the patient is being treated with a medication that induces gingival hyperplasia, alternatives to the drug should be explored in addition to recontouring of the gingiva.

These lesions often create a local environment between the GE and tooth surface that allows for rapid plaque and calculus accumulation; this space is referred to as a pseudopocket. Due to this phenomenon, it is common to encounter various stages of periodontal disease associated with the GE. In addition to resolving the GE, the course of treatment would depend on the stage of periodontal disease and the owner’s wishes, but could include surgical extraction or more conservative treatment options.

Gingival hyperplasia is typically recurrent, but the rate of recurrence can be reduced with effective plaque control. This is accomplished through daily home care and scheduled professional dental cleaning; the latter includes regular proactive resolution of pseudopockets through gingivoplasty from emerging gingival hyperplastic lesions, and is commonly performed annually.

Peripheral odontogenic fibroma

Peripheral odontogenic fibroma (POF) is also sometimes referred to as fibromatous epulis of periodontal ligament origin (FEPLO). There continues to be debate regarding the appropriate naming for this type of lesion 2, so to avoid contributing to the controversy the combined FEPLO/POF acronym will be used here. Clinically, these are typically exophytic, broad based, smooth in texture with an intact epithelium, but can have a cauliflower-like appearance (Figure 2). It is thought that the FEPLO/POF originates from the periodontal ligament-gingival attachment site, with a pathogenesis that includes some contribution of reactive hyperplasia 2. These lesions are differentiated from gingival hyperplasia/focal fibrous hyperplasia as they retain some features of periodontal ligament-derived fibroblasts in addition to the proliferative mesenchymal cells 2. Varying degrees of mineralization can be seen in FEPLO/POF lesions, which may represent cementum, bone or a combination of both. Although not a rule, displacement of dentition is more common in benign neoplasms such as FEPLO/POF. On diagnostic imaging (computed tomography or intraoral radiography), the lesion should not be seen to induce bone lysis (Figure 3), although periodontal bone loss due to the presence of the pseudopocket created by the FEPLO/POF may be present.

Recommendations regarding treatment of FEPLO/POF vary. Marginal excision may be adequate to resolve these lesions; however, tumor persistence is common and definitive therapy may include surgical extraction of the involved dentition with alveoloplasty and gingivoplasty of the FEPLO/POF origin, or en bloc resection 3.

Osteomyelitis

Treatment of osteomyelitis in the dentate maxilla or mandible (Figure 4) typically includes extraction of the associated dentition with harvesting of tissue samples for culture, debridement of the compromised tissues and administration of systemic antibiotics. I typically obtain a piece of compromise bone and submit it with instructions for maceration of the tissues, then aerobic and anaerobic culture and sensitivity to guide antibiotic therapy. Occasionally, resective surgery and an extended course of antimicrobials are required to resolve osteomyelitis, as some lesions will progress to osteonecrosis 4.

Alveolar bone expansion

Alveolar bone expansion (the clinical description) or chronic alveolar osteomyelitis (the histopathological diagnosis) is a bulging or thickening of the alveolar bone under the attached gingiva. It represents a chronic inflammatory state associated with periodontal disease and potentially tooth resorption 5, and is perhaps more common in cats than dogs. Typically, intraoral radiographs of the affected area will show vertical bone loss on the mesial and distal surfaces of the tooth, which can be confirmed with a periodontal probe; attachment loss is usually > 50%. This pattern of vertical bone loss is very commonly associated with alveolar bone expansion 6, but histopathology of the bone is required to confirm the suspected diagnosis. Treatment includes surgical extraction of the involved tooth, alveoloplasty and primary closure of the mucogingival flap. The attached gingiva is often thin and more firmly attached to the alveolar bone, and periosteal elevation should be performed with care to avoid perforation and formation of an oro-nasal fistula.

Acanthomatous ameloblastoma

Acanthomatous ameloblastomas (AA) are odontogenic tumors which have a basic structure that resembles the enamel organ (Figure 5). These tumors are considered locally destructive as they commonly cause regional bone invasion and are non-metastatic (Figure 6). Treatment most typically includes en bloc surgical resection. Historically, AA were described to have a high rate of tumor recurrence following resection, but a recent study has challenged this perspective; in a review of 263 patients with AA there was no evidence of tumor recurrence in any patients, even with 65.2% of patients having incomplete margins 7.

Papillary squamous cell carcinoma

Oral papillary squamous cell carcinoma (SCC) was historically considered a tumor of young dogs, but is now recognised to occur in dogs of all ages. This is a distinct type of SCC that is locally aggressive, as it often invades bone, but it does not appear to metastasize (Figure 7). It is generally considered less aggressive overall, and carries a relatively more favorable prognosis, than other forms of oral SCC. Treatment typically includes surgical resection with 10 mm margins to completely remove the gross and microscopic tumor cells. Radiation therapy is also considered a reliable treatment for this tumor type 8.

Squamous cell carcinoma

Treatment for mandibular and maxillary SCC (Figure 8) (specifically noting that this is non-tonsillar and non-papillary) typically consists of surgical resection with 10 mm margins. This tumor does have metastatic potential, and local tumor persistence risk is higher than with papillary SCC. In a study where 21 dogs received surgical treatment, 94% were alive at one year follow-up 8. Radiation therapy is considered the treatment of choice for non-resectable SCC 8.

Conclusion

The goal of this illustrated guide is to convey that there is a wide variety of possible diagnoses when an animal presents with a gingival enlargement. Although a practitioner can use patterns to guide their clinical impression, a diagnosis and prognosis should not be implied based on the physical appearance, and a full investigatory work-up is to be recommended for each case in order to best guide optimal treatment.