Plexiform ameloblastoma mimicking gingival enlargement: A case report

INTRODUCTION Ameloblastoma, is derived from the English word “amel” which means enamel and the Greek word “blastos” which means the germ. It arises from the epithelium of the dental lamina.¹

The peripheral ameloblastoma (PA) is an exophytic growth localized to the soft tissues overlying the teeth-bearing areas of the jaws.² It is a rare, benign, extraosseous and odontogenic soft tissue tumour that was first truly reported in the literature by Stanley and Krogh in 19594 In most cases there is no radiological evidence. ² The best treatment is an initial extended surgical excision.³

Case History

A 60-year old female patient was reported to the department. The patient presented with a painless swelling on the gingiva for 2 years (Fig.1). The patient was a known hypertensive for the last 4 years and was under regular medication and the nature of medication was unknown. She presented with a history of chewing of betel leaf, areca nut and tobacco since 10- 15 years. The intra-oral examination revealed a solitary swelling on the right mandibular front tooth region in relation to 42 and 43, which was measuring about 5 x 10-4mm in diameter. The swelling was firm in consistency with well-defined borders, non-tender and sessile (Fig.1). The peripheral radiograph examination displayed absence of any bone changes. On suspecting a soft tissue tumour, an excisional biopsy was performed. The specimen was fixed in 10% formalin buffer and it was sent for histopathological examination. OPG was taken to rule out the central form of ameloblastoma.

Histological changes

Haematoxylin and Eosin stain showed stratified squamous Para keratinised epithelium. The underlying tissue showed long anastomosing cord lined by tall columnar cells resembling ameloblastoma with peripherally placed nuclei and stellate reticulum cells over that. Numerous areas showed squamous metaplasia with keratin pearl formation (Gig.2). The above findings were suggestive of peripheral variant of plexiform ameloblastoma (PA).

Numerous areas of squamous metaplasia With keratin pearls

No recurrence was reported at the end of 2 months (Fig.3).

DISCUSSION

The PA is a rare, benign, and extraosseous odontogenic soft tissue tumour that was first reported in the literature by Kuru in 1911.¹Ameloblastoma is a locally aggressive epithelial odontogenic tumour, comprising 1.3%-10% of all ameloblastomas. The most frequent sites of PA are the upper and lower gingiva, with the buccal mucosa being an uncommon site.

Phillipsen and colleagues reviewed 160 cases of PA and observed that this tumour usually presented as a painless, sessile, firm growth with a smooth surface. In majority of the cases, there was no radiological evidence of bone involvement. They opined that the differential diagnosis should include soft tissue tumours such as peripheral giant cell granuloma, peripheral odontogenic fibroma, peripheral ossifying fibroma, papilloma and pyogenic granuloma.⁵

PA totally lacks the persistent growth of intraosseous ameloblastoma. It is less aggressive than intraosseous ameloblastoma and the term ‘PA’ can be potentially dangerous because the diagnosis can lead to an unnecessary aggressive treatment. Although the recurrence rate of PA is much lower (16%, 19%) than intraosseous ameloblastoma, a long-term follow up is required.

The present case a showed stratified squamous Para keratinised epithelium. The underlying tissue showed long anastomosing cord lined by tall columnar cells resembling ameloblastoma with peripherally placed nuclei and stellate reticulum cells over that. Numerous areas showed squamous metaplasia with keratin pearl formation. OPG was taken to rule out involvement of central ameloblastoma but the results showed no involvement of central part, suggesting it to be a peripheral variant of plexiform ameloblastoma.

Orsani et al. reported two cases of PA. The first patient was a 49-year-old male with a 2.5 cm diameter lesion in the premolar–molar left mandibular region. The second case was a 46-yearold patient with a 1.5 cm lesion in the mandibular premolar–molar site.⁶ Menon et al. reported a case of peripheral ameloblastoma of mandible.⁷ Kamil et al have made a systematic review on the management and prognosis of peripheral ameloblastoma.⁸

Chauhan et al reported a case of plexiform ameloblastoma of the mandible.⁹ The differential diagnosis usually includes pyogenic granuloma, peripheral giant cell granuloma, peripheral odontogenic fibroma, peripheral ossifying fibroma, papilloma, and epulis.¹⁰

CONCLUSION

Gingival enlargement may be inflammatory or non-inflammatory. A Plexiform ameloblastoma mimicking gingival enlargement is reported.

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