Introduction:
Peripheral odontogenic fibroma (POF) is an uncommon or rare benign tumor that affects the gingiva (gums) and is considered the equivalent of a central odontogenic fibroma that occurs outside the bone. It is often confused as a clinical entity with peripheral ossifying fibroma that is more common in occurrence.
What Is Peripheral Odontogenic Fibroma (POF)?
Odontogenic fibroma is a distinct type of tumor classified by WHO (World Health Organization) as a neoplastic and fibroblastic lesion that not only contains varying amounts of inactive odontogenic epithelium but may also be composed of dentine or material that resembles the cementum layer of the tooth root. This lesion as a clinical entity was first described in 1982 by Gardner who in detail elaborated on the nature of the lesion as either peripheral odontogenic fibroma (the extraosseous fibroma) or the central type of odontogenic fibroma. According to dental research and clinicopathological studies, POF type comprises approximately 1.2 percent of all major cysts and tumors that stem from odontogenic origins. The dental literature consists of rare case reports of presentations of the same lesions. Clinically they may be indiscernible from other fibrous lesions of the gingiva occurring in the oral cavity. Additional tissue analysis also would be deemed necessary by the dental or the oral and maxillofacial surgeon in order to establish a confirmatory diagnosis of this distinctive benign tumor.
Where Is Peripheral Odontogenic Fibroma Commonly Seen?
Peripheral odontogenic fibroma starts as a visible gingival growth within the mouth most commonly near the gum line and is closely associated with the tooth. It appears as a smooth, pink, expansive but can be cauliflower as well. It is most commonly located in front of the upper jaw and second most common being the back of the lower jaw.
What Causes Peripheral Odontogenic Fibroma?
The peripheral odontogenic fibroma is indeed an uncommon gingival mass but quite distinctive and comes across as a challenging diagnostic lesion. This condition or tumor affects people across a broad age range with no relative prediction. These lesions are often confused with the lesions of the peripheral ossifying fibroma because, in contrast to the peripheral ossifying fibroma, the peripheral odontogenic fibroma is quite rare in prevalence, as per case reports.
There is no specific gender preference and can occur in any age group of patients ranging from 5 to 65 years. However, some case reports are based on this disease or tumor occurring more in the second decade of life. Most commonly it can be observed in the lower jaw or mandible in comparison to the upper jaw or maxilla. The lesions are distinctive, slow growing, solid in consistency, and may present themselves clinically as firmly attached gingival masses. These gingival masses may arise in between the teeth in some cases, causing potential displacement of the tooth surrounded by the lesion. The lesions are composed of cellular and fibrous connective tissue parenchyma. The characteristic feature is non-neoplastic islands, "strands of clouman," and the cuboidal pattern epithelium observed histopathologically is also odontogenic.
What Are the Clinical Features?
Clinically, the lesions are relatively uncommon, benign, and unencapsulated. These exophytic masses in the gingiva may be either sessile or pedunculated types with red or pink appearance and a smooth surface. Ulcerated lesions are also possible with this tumor.
The typical location predominantly is the attached gingiva of the premolar and molar regions, with even distribution within the jaw (maxilla or the mandible). On palpation, the lesions tend to be usually firm and non-tender. These lesions in POF may be either diffuse or of a multifocal type. The diffuse type may be associated with ocular and skin lesions. The histologic subtypes are more complex that may be either the granular or the squamous cell carcinoma variant.
What Are the Radiological Features?
In peripheral odontogenic fibroma, radiographic changes in the bone are not apparently found as these fibromas are small lesions which occur extraosseous within the gingiva. In certain saucerization of the cortical bone or widening of the periodontal ligament space at the cervical region may be seen. Within few lesions of peripheral odontogenic fibroma, numerous foci of small radiopaque masses are sometimes seen which will indicate calcifications within the tumor.
What Is the Differential Diagnosis?
These lesions need to be distinguished from other exophytic lesions, the most common being peripheral ossifying fibroma to which there is a particular resemblance. However, it is crucial to distinguish it from other lesions, such as:
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Fibrous hyperplasias.
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Peripheral giant cell granulomas.
The clinical behavior of POF is very different from other lesions because of the exophytic, non-malignant or benign nature of the lesions. In addition, due to the immense epithelial proliferation in these lesions, POF diagnosis is even more difficult histologically with the various peripheral types of ameloblastoma tumors or calcifying epithelial odontogenic tumors (CCOT).
However, the pathologist may observe that the epithelial islands occurring in POF are much smaller than those in ameloblastoma tumors. In contrast to cancerous tumors, these epithelial islands do not exhibit hyperchromatism or possess any intracytoplasmic vacuoles. In addition, the polarization of the nucleus is away from the basement membrane within the basal cell layer. The differentiation that needs to be done is by the presence of hard tissues (dentin or cementum) in this tumor that is characteristically found, which are not observed in ameloblastoma. However, the consideration is that not all peripheral odontogenic fibromas, owing to their distinctive subtypes, may have hard tissue like dentin or cementum always; exceptions are present clinically wherein no bony or tooth-like material may be present.
How Is Peripheral Odontogenic Fibroma Treated?
Peripheral odontogenic fibroma is mainly treated by simple surgical excision by the dentist or the oral and maxillofacial surgeon by eliminating the clear margins of the benign tumor preliminarily observed by histopathology. However, recurrence is possible for up to four years after the initial excision, as per the case reports. Therefore, the dentist or periodontist can also recommend mucogingival grafting when there is a gross or extensive involvement of the exophytic lesion over the attached gingiva.
Conclusion:
Thus, POF or peripheral odontogenic fibroma, a rare distinctive and benign tumor of odontogenic origin, is challenging to diagnose by the clinician or the dentist and requires surgical resection and even gingival grafting for not only maintaining the patient's periodontal and dental health but also the facial esthetics.
