Solitary Neurofibroma of Mandible in a 2-Year-Old Child: A Rare Case Report and Review of Literature

Abstract

Solitary intraosseous neurofibromas of mandible are very rare and only 40 cases are documented. This case report presents one of the youngest documented case of solitary neurofibroma of mandible, in a 2-years old male child. The tumour was symptomatic and presented as a swelling over right posterior region of mandible. The patient underwent conservative excision under general anaesthesia. The inferior alveolar nerve was preserved. Histopathology was suggestive of benign nerve sheath tumour. Immunohistochemistry showed moderate S-100 and strong CD34 positivity. Postoperative healing was uneventful. This report also reviews forty previously reported cases of solitary intraosseous neurofibromas of the mandible.

Introduction

Neurofibromas are benign tumours of the peripheral nervous system. In the head and neck region neurofibromas mostly manifest as cutaneous lesions (81.2% cases) [1]. Neurofibromas of the oral cavity are infrequent (5.6% cases) and usually occur in association with the branches of trigeminal and facial nerves [2]. However, intraosseous manifestation of such tumours in gnathic skeleton is extremely rare and only 40 cases have been documented in the literature so far [3]. The purpose of this case report is to present a case of solitary neurofibroma of mandible in a young child and review the clinical, radiographic and immunohistochemical features of this rare jaw tumour.

Case Report

A 2.5-years-old boy presented with a swelling over right angle region of mandible which has been there for last 7–8 months. The patient complained of intermittent pain during mastication which has been present for last 15 days. The patient’s past medical and family histories were unremarkable.

On physical examination, a well-defined, smooth-surfaced, firm mass was palpated in the right ramus-body region of mandible (Fig. 1). The swelling caused displacement of the regional deciduous molar teeth.

Fig. 1.

Preoperative photo of the patient have swelling over right lower jaw

Contrast enhanced magnetic resonance imaging (MRI) revealed a well-defined expansile solid-cystic lesion of size 37 × 35 × 34 mm involving the right hemi-mandibular body, alveolus and ramus with evidence of cortical erosion (Fig. 2). A small cystic component was found inside the lesion posteriorly with tooth-like structures within. The soft tissue component appeared T1 hypo-intense and T2/STIR hyper-intense and showed mild homogenous enhancement on post-contrast study (Fig. 3). Considering the young age of the patient the authors have chosen MRI over CT scan for imaging of the lesion. Propofol was used by the anaesthetist for sedation of the patient during MRI.

Fig. 2.

An axial T1-weighted magnetic resonance image showing a well-defined expansile solid-cystic lesion (white arrows) involving the right hemi-mandibular body, alveolar process and ramus with evidence of cortical erosion

Fig. 3.

A sagittal T1- weighted magnetic resonance image showing mild homogeneous enhancement on postcontrast study. A small cystic component was found inside the lesion posteriorly (black arrow)

Taking into account the age of the patient and clinico-radiographic features of the lesion, the authors considered vascular malformation, Ewing’s sarcoma and rhabdomyoma as possible differential diagnosis for this lesion.

The patient underwent an incisional biopsy under general anaesthesia. Aspiration of the tumour was done on the operating table and it turned out to be negative for blood. Histopathological examination of the surgical specimen revealed benign spindle cells present in vague, storiform pattern within a collagenous matrix (Fig. 4). Mast cells were also found in significant numbers. The microscopic examination was suggestive of a benign neural sheath tumour (BNST). There was no microscopic evidence of malignancy or presence of verocay bodies.

Fig. 4.

Histopathologic examination with hematoxylin and eosin (H&E) stain showing benign spindle cells present in a vague, storiform pattern within a collagenous matrix; magnification 200x

Finally, definitive surgery was done where excision of the tumour was done with careful blunt dissection in order to preserve the inferior alveolar nerve. Macroscopically the tumour appeared as a solid, greyish-white mass (Fig. 5). The tooth-like structure appeared to be the calcified tooth bud of the permanent first molar tooth. The surgical wound was irrigated and closed in layers. The postoperative healing was uneventful. The postoperative histopathology results were similar to that of incisional biopsy.

Fig. 5.

Macroscopic appearance of the resected tumour mass

Immunohistochemically, evaluation showed multifocal and moderate positivity for S-100 stain signifying the neural origin of the tumour (Fig. 6). Tumour cells also exhibited diffuse and strong cytoplasmic and membranous positivity for CD34 (Fig. 7). MIB-1 revealed a low proliferative index of 5% for the tumour thus, excluding its malignant nature. The immunohistochemistry was suggestive of neurofibroma.

Fig. 6.

Immunohistochemical examination showing multifocal and moderate positivity for S-100 stain

Fig. 7.

Immunohistochemical examination also showed diffuse and strong cytoplasmic and membranous positivity for CD34

Discussion

Neurofibromas are formed by a complex proliferation of Schwann cells, perineural hybrid cells, intraneural fibroblasts and intermediate cells [1]. Posterior mandible is the most common site of manifestation of solitary intraosseous neurofibromas. This predisposition may be due to the long thick bundles of the inferior alveolar nerve found in the posterior mandible [4]. These tumours show a marked female predilection. The average age of presentation is 27.5 years. This case represents one of the youngest case of solitary intraosseous neurofibroma of mandible ever reported in the literature [3]. In fact, this is the youngest reported case of neurofibroma of mandible from the Indian subcontinent.

Neurofibromas show higher local recurrence than other BNST like schwannomas. This may be due to the lack of encapsulation of neurofibromas, which makes complete extirpation of the tumour more difficult [5]. Due to this reason many researchers practice radical resection neurofibroma along with sacrifice of the involved nerve. However considering the age of patient and postoperative sensory loss, the authors performed a more conservative excision by preserving the inferior alveolar nerve with careful surgical dissection using magnifying loupes. It has been seen that even if these tumours are incompletely excised, the residual lesion regrows so slowly that a long-lasting gain is attained.

Histologically, neurofibromas should be differentiated from other spindle cell lesions like spindle cell carcinoma, amelanotic melanoma, traumatic neuroma, schwannoma [6]. Traumatic neuroma was ruled out since the patient did not give any positive history for trauma. The absence of verocay bodies and the presence of mast cells and fine fibrillary collagen matrix distinguished neurofibroma from schwannoma. Table 1 provides a detailed literature review of all forty cases of solitary mandibular neurofibromas reported till date.

Table 1.

Summary of reports of solitary intraosseous neurofibromas of mandible

References	Age (years)/gender	Site	Radiographic features	Immunohistochemistry features
Present case	2.5/M	Body-ramus	Well-defined expansile solid-cystic lesion with evidence of cortical erosion in MRI. Mild homogenous enhancement was seen on post-contrast study	S-100 multifocal and moderately positive, strong CD34 positivity EMA, cytokeratin, CD31, SMA, STAT-6, TLE-1 and HMB-45 negative MIB-1 index low
Behrad [6]	32/F	Body	Unilocular expansile radiolucency involving mandibular canal	Not reported
Iqbal [7]	13/M	Body-angle	Ill-defined radiolucency with respect to teeth #46 and 47	S-100 positive
Inoue [8]	27/M	Ramus and infratemporal fossa	MRI-Large mass in the infratemporal fossa, extending from the intra-mandibular region to the foramen ovale. The mass exhibited no enhancement in post-contrast study	S-100 positive, EMA negative
Narang [9]	45/F	Symphysis-ramus	Irregular radiolucency involving mandibular canal	S-100 positive, MIB-1 negative
Fortier [3]	70/F	Body	Well-defined unilocular radiolucent region involving the mandibular canal	S-100 positive
Gujjar [10]	28/F	Body	Homogenous radio-opacity surrounded by a thin uniform radiolucent border	S-100 positive
Saravani [11]	39/F	Body	Relatively well-defined unilocular radiolucency	S-100 positive
Jagnam [12]	62/F	Right body-left body	Wel-defined radiolucency with thinning of lower border and pathological fracture in left region	S-100 positive
Diechler [13]	14/M	Ramus	Unilocular radiolucency	Tumour cells: vimentin positive, neuroespecific enolase (NSE) positive and anti S-100 negative Residual nerve fibres: S-100 positive; NSE positive
Tao [14]	16/F	Ramus	Multilocular radiolucency with irregular edges	S-100 positive
Vivek [4]	39/F	Symphysis-parasymphysis	Well-circumscribed radiolucent area involving the mandibular canal	S-100 positive
Apostolidis [5]	67/F	Body-ramus	MRI- Well-defined soft tissue lesion causing erosion of buccal cortex	Not reported
Alatli [15]	37/F		Not reported	Not reported
Ueda [16]	37/M	Body	Unilocular radiolucency	S 100 positive
Papageorge [17]	4.5/M	Ramus-infratemporal fossa	Well-defined unilocular radiolucency continuous with inferior alveolar canal	S-100 protein and vimentin positive
Weaver [18]	22/F	Body	Well-circumscribed unilocular radiolucency	S-100 positive
Polak [19]	60/M	Body	Unilocular radiolucency involving the mandibular canal	S-100 and anti-Leu positive
Papadopoulos [2]	15/M	Body	Unilocular radiolucency near mental foramen	Not reported
Gnepp [20]	24/F	Body	Non expansile, moderately well-defined unilocular radiolucent lesion	Not reported
Gnepp [20]	39/F	Body	Well demarcated, slightly expansile, unilocular radiolucent lesion	Not reported
Larsson [21]	25/F	Body-ramus	Well-defined large radiolucency	Not reported
Larsson [21]	46/M	Body	Osteolytic radiolucent lesion with slightly radiopaque borders	Not reported
Ellis [22]	41/F	Body-ramus	Poorly defined multilocular radiolucent lesion	Not reported
Ellis [22]	4/F	Body	Well demarcated radiolucent lesion	Not reported
Ellis [22]	8/M	Body-angle	Well demarcated radiolucent lesion with sclerotic borders	Not reported
Ellis [22]	23/F	Body-ramus	Radiolucent-radiopaque lesion with indistinct borders	Not reported
Ellis [22]	4/M	Body	Multilocular radiolucent lesion	Not reported
Singer [23]	30/F	Posterior mandible	Radiolucent fusiform lesion	Not reported
Cundy [24]	55/F	Body-angle	Unilocular radiolucency	Not reported
Prescott [25]	5/M	Body	Circumscribed radiolucent lesion	Not reported
Cassalia [26]	16/F	Angle	Multilocular radiolucency involving mandibular canal	Not reported
Sharawy [27]	22/F	Body-angle	Multilocular expansile radiolucency	Not reported
Gutman [28]	5/F	Body	Multilocular expansile radiolucency	Not reported
Villa [29]	17/F	Body	Osteolytic radiolucent lesion	Not reported
Caldwell [30]	2.5/M	Body	Radiolucent lesion	Not reported
Johnson [31]	34/F	Body	Radiolucent lesion	Not reported
Cornell [32]	65/F	Body	Cystic lesion with ill-defined borders	Not reported
Bruce [33]	36/M	Body	Well-defined radiolucency involving mandibular canal	Not reported
Blackwood [34]	41/M	Body	Unilocular radiolucency	Not reported
Goldman [35]	33/M	Body-ramus	Unilocular radiolucency	Not reported

Conclusion

Maxillofacial surgeons should be aware of the possibility of intraosseous neurofibromas during diagnosis of spindle cell lesions in mandible and should perform appropriate immunohistochemical tests to identify them. Recognition of neurofibromas is important as it may be the initial manifestation of neurofibromatosis. Patients with solitary neurofibromas of mandible should be kept under long term follow-up postoperatively as these tumours have tendency of local recurrence and malignant transformation.