Peripheral Ossifying Fibroma Veiling a Nasopalatine Duct Cyst: An Unusual Concurrence

Abstract

We hereby report an unusual case which presented as a routinely encountered reactive lesion on the palate, whilst the radiological examination revealed a radiolucent cystic lesion underneath. After the investigations from radiography to histopathology, it was finally diagnosed as a peripheral ossifying fibroma coexisting with a nasopalatine duct cyst.

Introduction

The peripheral ossifying fibroma (POF) is a benign reactive gingival lesion presenting as a pink or bright red, sessile or pedunculated mass [1]. Nasopalatine duct cyst (NPDC) is the most common non-odontogenic cyst of the jaws. It is most often detected in the second to fifth decades of life as asymptomatic swellings of the palate but may present with painful swelling or drainage [2]. POF occurring in simultaneity with NPDC is a rare occurrence and has not been reported in the literature so far.

This report documents one such case.

Case Report

A 35-year-old female reported with a three-month history of a slow growing, painless mass on the palate with occasional impingement on the mass, by mandibular anterior teeth. On examination, the lesion presented as a solitary, well-defined, pink to red coloured, pedunculated growth on the hard palate, palatal to 11, measuring about 1.2 × 1.8 cm. It had an irregular surface with visible indentation of opposing teeth, was firm in consistency and non-tender. (Fig. 1) She had a poor periodontal status with presence of generalized gingival inflammation, calculus deposits and recession. Based on these findings a presumptive diagnosis of traumatic fibroma was formulated.

Fig. 1.

Intra-oral photograph showing well-defined growth on the palate

A periapical radiograph was made to evaluate any changes in the underlying bone, which surprisingly revealed a well circumscribed, non-corticated ovoid radiolucency of approximately 1.8 cm × 0.8 mm in size, in the apical and interdental region of 11 and 21 suggestive of NPDC.

The visible soft tissue pathology was biopsied under local anaesthesia. The histopathology revealed hyperplastic hyperparakeratinised stratified squamous epithelium. Deeper trabeculae were seen with prominent reversal lines and peritrabecular clefting admixed with fibroblastic infiltrate, suggesting a diagnosis of Peripheral ossifying fibroma. No histopathological elements of a cyst were seen.

Thereafter, a Cone Beam Computed Tomography was performed for an elaborate view of the cystic pathology and to confirm whether its origin was from the incisive canal or periodontal region.

Axial sections revealed a well circumscribed oval hypodensity measuring 7.8 mm × 6.5 mm is size in the interradicular and apical region of 11 and 21. Vertically, the pathology measuring 15.9 mm in size, extended 2 mm above the alveolar crest to the anterior nasal spine. In the sagittal section, there was a fusiform enlargement of the incisive canal, more evident towards the palate. (Fig. 2) So, the radiographic findings of a nasopalatine duct cyst were confirmed. Adopting a palatal approach, an enveloping flap from 14 to 24 was raised and the cyst was surgically excised under local anaesthesia. The histopathology revealed tissue covered by ciliated pseudostratified columnar epithelium. The cyst wall was fibrous, showed moderate inflammatory reaction, numerous nerve bundles and thick-walled blood vessels with few adipocytes. Thus, the case was diagnosed as a peripheral ossifying fibroma occurring concurrently with a nasopalatine duct cyst.

Fig. 2.

a Coronal and b Sagittal c CBCT views showing a well circumscribed oval hypodensity

Discussion

The origin of POF is not clearly defined but it is believed to arise from the gingival corium, periodontium or periodontal membrane [3]. Majority of the lesions have some kind of chronic irritation or low-grade injury such as presence of calculus, sharp edges of teeth or restorations, chewing habits as the triggering factor for its development [4].

Radiographic findings of few reported lesions of POF include migration of the adjoining teeth and loss of interdental bone. Other insignificant radiographic changes reported are superficial erosions and foci of calcifications [1]. In our case, interdental bone loss of the adjoining teeth and an unusual well-defined radiolucency at the exact site of the clinical lesion was seen which was later proven to be an NPDC.

Nasopalatine duct cyst (NPDC) is a non-odontogenic, developmental cyst of the maxilla with an unclear etiology. It is believed to arise either from the epithelial remnants of nasopalatine duct from the vomer nasal organ of Jacobson. Trauma and infection may act as initiating factors for its development [5].

Histologically, NPDC shows a multitude of epithelium type– lesions close to the nasal floor generally have ciliated columnar epithelium and squamous epithelium is seen in the ones which are in proximity to the oral cavity. [5]. In our case, the cystic lining was of pseudo-columnar type, which may be attributed to the proximity of the lesion to the nasal cavity, as evident on the radiograph.

Surgical excision of the clinically visible soft tissue pathology was done in the first intervention. This enabled the authors to confirm the diagnosis of the peripheral lesion and its relation with the underlying bony pathology. Histopathology showed typical findings of a POF and no traces of cystic epithelium were visible in the sample. Since, both POF and NPDC have chronic irritation as one of the underlying etiological mechanisms, the presence of periodontal bone loss and calculus may have stimulated both periodontal as well as nasopalatine duct epithelial cells to develop into the respective pathologies, simultaneously. This led us to infer that the POF was a mere concurrent finding with NPDC in the present case. Secondly, the presence of pseudo-columnar epithelial cells in the cystic lining of NPDC, confirms its origin from the remnant cells towards the nasal end of the duct. Though less convincing, another hypothesis that may be proposed here is that the outer capsule of NPDC is composed of dense fibrous tissue. So, the POF may have been an extended outgrowth of this fibrous reaction, which may have appeared as separate entity owing to two separate surgical interventions for the peripheral and central pathology.

Whether overlapping etiological factors led to the concurrence or did POF occur secondary to the presence of NPDC, is still ambiguous. This is riveting and paves way for further sighting with regards to the origin of the two lesions, without ruling out the possibility of it being merely coincidental. To the best of our knowledge there has been no other concurrence involving these two lesions in the oral cavity.

Conflicts of interest

The authors have no conflicts of interests to declare.

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Authors' Contributions

All authors made substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data; or the creation of new software used in the work and drafted the work or revised it critically for important intellectual content.

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