Gingival neurofibroma : A rare case report

INTRODUCTION

Neurofibroma is the most common type of peripheral nerve neoplasm derived from mixture of cell types including schwann cells and perineural fibroblasts.¹ The first description of solitary neuro fibroma of the oralcavity was given by Brucein 19542,3. According to Shklar and Meyer classification (1963) neuro fibroma is seen either as a solitary lesion or as a part of thegeneralized syndrome of neurofibromatosis (von Recklinghausen’s disease of the skin)⁴ . The solitary type maybe central or peripheral⁴ . The cell of origin for neuro fibromahas not yet be endefinitively identified but is generally believed to arise from the perineural fibroblast which areneuroectodermal in origin. The cause of solitary type is still unknown⁵ .

Clinically neurofibroma appears as discrete, nonulcerated nodule, which tends to be of the same color as the normal mucosa. Neurofibromas are common on the skin but are rare intraorally. When it occurs introrally, it is usually seen on the tongue, lips or mucosa of hard palate; occasionally on the buccal mucosa, edentulous alveolar crest and floor of mouth as well as in the tonsillar area, nasopharynx, submandibular area and the neck⁵ .

The great clinical significance of neurofibromas aside from cosmetic problem lies in fact that in some patients malignant transformation may occur. However solitary neurofibromas seldom undergo malignant transformation. A thorough literature search shows only 7% cases of neurofibromaongingiva⁵ . Hence the need for reporting such a rare case of neurofibroma is emphasized inpresent case report.

CASE REPORT

A 45-year-old male patient reported to department of Periodontology with a chief complaint of a painless round soft tissue growth on the gums in the lower front region of the mouth which was aesthetically unpleasant [Figure1.A].The growth started one year back which gradually increased to the present size.

Intraoral examination showed a firm pedunculated non tender growth on the buccal gingiva of left mandibular canine and first premolar [Figure1. A].The growth was pink in colour, smooth and shiny approximately 1cm x 1.5cm in diameter [Figure1. B]. Intraoral periapical radiographic examination did not reveal any bony involvement.

Based on the history and clinical examination the lesion was provisionally diagnosed as irritational fibroma. The differential diagnosis included soft tissue lesions like fibro- epithelial polyp, pyogenic granuloma, peripheral giant cell granuloma, peripheral ossifying fibroma and other benign neoplasms.

The patient underwent complete haemogram before surgery which were within normal limits. For surgical excision, local anaesthesia was given using 2% lignocaine with 1:80,000 adrenaline. The growth was surgically excised from the base with the help of no. 15 blade [Figure1. C]. For comparing it with normal tissue 2 mm of healthy tissue was excised along with it [Figure1. D]. Periodontal pack was given for 1 week, followed by postoperative instructions. Patient was prescribed analgesic twice daily for 3 days and 0.2% chlorhexidinegluconate for rinsing twice daily.

On histopathologic examination, Haematoxylin and eosin stained [Figure 3. A and 3. B]sections showed lesional tissue covered by stratified squamous parakeratinized epithelium. The lesional tissue was well circumscribed and predominantly showed spindle to stellate shaped cells with elongated wavy nuclei. The cells were seen in association with delicate collagen fibres and fibroblasts [Figure 3. A and 3. B]. Numerous mast cells were seen throughout the lesional tissue. Presence of mast cells was confirmed by toluidine blue staining [Figure 3. C]. The lesional cells were positive for S-100 protein as analysed by immunohistochemistry [Figure 3. D]. Based on these findings, a final diagnosis of neurofibroma was established.

At one week follow up visit [Figure2. A], there were no postoperative complications. Patient wasrecalled after one month [Figure 2. B], three month [Figure 2. C] and six month [Figure2. D] post operatively and there was satisfactory healing with norecurrence.

DISCUSSION

Neurofibroma, though not a common disease, is by no means a clinical rarity. It is inherited as a simple autosomal dominant trait with variable penetrance and a 50% mutation rate. It occurs with frequency of one case in approximately 3000 births in the general population.⁵

It is usually seen in third decade of life, although a wide range of occurrence between 10months to 70 years has been reported by Cherrik & Eversole⁶ . The gender predilectionis still debatable² . The present case was reported in a 45 years old male patient. Maruyama et al reported the following distribution of 66 neurofibromas in the facial region; tongue(n=12), palate(n=12), mandibular ridge/ vestibule(n=15), maxillary ridge/vestibule(n=9), buccal mucosa(n=10), lip(n=4), mandible(n=2) and gingiva(n=1)⁶ . The present case revealeda painless, firm, pedunculated lesion on buccal attached gingiva, which is a rare location for neurofibroma .

Neurofibroma exhibits considerable variation on histologic structure but is generally composed of proliferation of spindle cells with thin, wavy nuclei intermingled with neurites in an irregular pattern as well as delicate, interwining connective tissue fibrils. Cellular and myxoid patterns are predominate. Melanocytes may sometimes be found and mast cells are common⁵ .

hepresent cases how edspindle to stellate shaped cells with elongated wavy nuclei on haematoxylin and eosin stain and mast cells on toluidine blue stain.

The lesional cells are uniformly positive for S100 protein, signifying that they originate from neural crest derived tissue and this was also confirmed in the present case by S-100 positivity. Antibodies to epithelial membrane antigen, CD57 and collagen are used only when histologic differentiation with other neural tumorsis difficult⁵ .

Treatment of choice for neurofibroma is surgical excision, to conserve the nerve from which the tumor originates. Malignant transformation of solitary neurofibroma is extremely rare⁷ . Regular follow up should be done for any recurrence^[5].In present case six months follow up was uneventful.

Thus, we present an unusual case of neurofibroma mimicking fibromatous enlargement. The need for reporting these rare case is to make clinicians aware of such presentation. If the diagnosis is based only on clinical and radiographic features, it can be erroneous. Hence histopathological examination is necessary to reach an appropriate diagnosis and to render accurate treatment.