Journal of Otology & RhinologyISSN: 2324-8785

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Case Report, J Otol Rhinol Vol: 4 Issue: 5

Intraosseous Schwannoma (Neurilemmoma): An Unusual Anterior Maxillary Swelling: A Case Report and Review of Literature

Balram Garg1*, Jitender Batra1, Radhika Chavda2, Gyanender Attresh1 and Mohit Agrawal3
1Department of oral and maxillofacial surgery, PGIDS, Pt. BD Sharma University of Health Sciences, Rohtak, Haryana, India
2Department of Conservative Dentistry and Endodontics, GDC & H, Ahmedabad, Gujarat, India
3KD Dental College and Hospital, Mathura, Uttar Pradesh, India
Corresponding author : Dr. Balram Garg
Department of oral and maxillofacial surgery, PGIDS, Pt. BD Sharma University of Health Sciences, Rohtak, Haryana, India
Tel: 08221842525/09173438798
E-mail: [email protected]
Received: February 06, 2015 Accepted: October 06, 2015 Published: October 09, 2015
Citation: Garg B, Batra J, Chavda R, Attresh G, Agrawal M (2015) Intraosseous Schwannoma (Neurilemmoma): An Unusual Anterior Maxillary Swelling: A Case Report and Review of Literature. J Otol Rhinol 4:5. doi:10.4172/2324-8785.1000247

Abstract

Neurilemmoma, also known as schwannoma, are benign tumors of the nerve sheath arising from proliferation of perineural schwann cells. Approximately 25% to 45% of the schwannoma are seen in the head and neck region and are found rarely (1-12%) in the oral cavity. Intraoral schwannoma are relatively uncommon and intraosseous ones are even rarer. The intraosseous lesions account for less than one percent of the central neoplasms. This case report presenting an interesting case of an intraosseous schwannoma unusually located in anterior maxilla of 58 years old female patient along with it review of literature.

Keywords: Benign neoplasm; Intraosseous; Schwannoma

Keywords

Benign neoplasm; Intraosseous; Schwannoma

Introduction

Schwannoma is a solitary, encapsulated benign tumor arising from the perineural schwann cells of the nerve sheath of ectodermal origin. [1,2]. It was first described by Verocay in 1910, called this benign neurogenic tumor as “Neurinoma” [3]. In 1935, the term “Neurilemmoma” was coined by Stout [4]. Clinically it manifests as a solitary and slow growing asymptomatic firm mass with a smooth surface; although symptomatology depends on the nerve of origin [1,5]. Schwannoma is usually found in the head and neck region with rare occurrence in oral cavity and intraosseous ones are even rarer. The intraosseous lesions account for less than one percent of the central neoplasms [6,7].
We report here a case of an intraosseous schwannoma unusually located in anterior maxilla of 58 years old female patient.

Case Report

A 58 year old female patient reported in the department of Oral & Maxillofacial Surgery with chief complaint of swelling over upper front jaw region since one year. History revealed that the swelling had gradually increased in size since its onset. It was not associated with pain, any discharge or paresthesia. She had undergone extraction of upper anterior teeth one year back. Her family and medical history were not contributory. Extra oral examination revealed a single diffuse painless swelling obliterating right nasolabial fold (Figure 1). Intraorally, a single diffuse swelling of approximately two x two cm in diameter extending from the apical region of upper right canine to the apical region of upper left lateral incisor crossing midline with obliteration of the upper labial vestibule was noticed. The swelling was non tender, fixed and firm to hard in consistency on palpation and the overlying mucosa was normal without erythematous or ulcerative changes. There was no sinus, fistula or puncture mark. Extra oral radiographic examination revealed a single well defined radiolucency of approximately two cm in diameter with sclerotic border extending from upper right canine to upper left canine with root resorption of upper right canine and right lateral incisor (Figure 2). All the teeth were vital. Thus, after clinical and radiographic examination, a provisional diagnosis of jaw cyst was made.
Figure 1: Preoperative photograph shows swelling at upper lip with obliteration of upper labial sulcus.
Figure 2: Preoperative x-ray orthopentomogram shows a single well defined radiolucency with sclerotic border extending from upper right canine to upper left canine.
Surgical excision of lesion under local anaesthesia was planned and the mass was excised (Figure 3) without complications. Excised mass was sent for histopathological examination. On histopathologic examination, a well defined neural lesion surrounded by a thin fibrous connective tissue capsule was found (Figure 4A). The tumour mass consisted of neural tissue predominantly composed of closely packed spindle shaped cells arranged in palisading pattern with homogenous eosinophilic areas resembling Verocay bodies as seen in Antoni A type tissue while irregularly arranged Antoni B type tissue was also seen (Figure 4B). With these histopathologic features confirmed diagnosis of schwannoma was made.
Figure 3: Preoperative x-ray orthopentomogram shows a single well defined radiolucency with sclerotic border extending from upper right canine to upper left canine.
Figure 4: (A) Haematoxylin and eosin (10x) stained section shows a well defined neural lesion surrounded by a thin fibrous connective tissue capsule; (B) Haematoxylin and eosin (40x) stained section shows closely packed spindle shaped cells arranged in palisading pattern with homogenous eosinophilic areas resembling Verocay bodies as seen in Antoni A type tissue while irregularly arranged Antoni B type tissue.

Discussion

Neurilemmoma, also known as schwannoma, are benign tumors of the nerve sheath arising from proliferation of neuroectodermal Schwann cells that cover myelinated nerve fibres and can occur along any somatic or sympathetic nerve (except olfactory and optic nerves) that contain schwann cells [4,5]. Origin of schwannoma has long been debated. Some says its origin directly from neural tube and some says its origin from neural crest [8]. Etiology is still unknown and mostly they are asymptomatic [1]. It is an encapsulated benign neoplasm that typically presents as a solitary, firm mass with a solid to partly cystic gross appearance [9]. Clinically tumor can affect all ages but peak incidence is between 30 to 60 years of age [10]. Chi et al. reported that schwannoma of the jaw occurs in the age range of 8-72 years, with the average age of 34 years with definite female predilection. This article also presents the case of female patient aged 58 years old with painless asymptomatic swelling.
The neoplasm has a predilection for the head, neck and flexor surfaces of upper and lower extremities. Two types of schwannoma are distinguished (central and peripheral) located in bone and soft tissues respectively [11]. Approximately 25% to 45% of the schwannoma are seen in the head and neck region and are found rarely (1-12%) in the oral cavity [12]. Most of the intraoral schwannoma are located in the tongue with a predilection for the anterior portion followed by the palate, floor of the mouth, oral mucosa, gingivae, lip and buccal mucosa [3,13,14]. Very rarely, the tumour arises centrally with in bone (<1%) and may produce bony expansion [15-19]. Intraosseous schwannoma are most common in the posterior mandible involving body and the ascending ramus and can also involve the symphysis region and usually appear as either unilocular or multilocular radioluciencies on radiographs [5,7]. Additional features such as external root resorption, thinning of bony cortex and peripheral scalloping can be evident. Pain and paresthesia are not unusual for intraosseous tumors [10]. The literature revealed 45 reported cases of central schwannomas in either of the jaws; 40 in the mandible and 5 in the maxilla [7,11]. The presented case add an another interesting case of intraosseous schwannoma to the literature which is in contrary to its usual location of occurrence, found in the anterior maxilla [7,10].
The initial diagnosis of schwannoma is difficult because of the rarity of this condition and the lack of specific symptoms and signs associated with these tumors [20]. Ultrasonography, computed tomography and magnetic resonance imaging may be useful as an diagnostic and treatment tools because it not only determine the extent of lesion but also shows its relationships to the vessels and associated important structure. But most intra oral tumours present as relatively small lesions, so establishing the differential diagnosis using the above mentioned methods have previously proven to be not necessary (Asaumi et al.). In most patients, a definite diagnosis is made from histological findings as like in this presented case diagnosis was confirmed after histopathological examination. Histological finding of this presented case was similar to those presented previously in various literatures consisting of a well defined neural lesion surrounded by a thin fibrous connective tissue capsule and tumoral proliferation by two types of tissues: Antoni type A and Antoni type B. Haematoxylin and eosin (40x) stained section shows closely packed spindle shaped cells arranged in palisading pattern with homogenous eosinophilic areas resembling Verocay bodies as seen in Antoni A type tissue while irregularly arranged Antoni B type tissue. Histologically five variants have been described: common, plexiform, cellular, ancient and epitheloid schwannoma.
The differential diagnosis of schwannoma includes malignant tumors, inflammatory and cystic lesions and numerous benign epithelial and connective tissue tumors. In our patient, malignant and inflammatory lesions were excluded because of clinical appearance and radiographic features. Fine needle aspiration cytology excluded haematological or other cystic lesion.
Surgical excision of the tumor [7,10] is the main treatment for schwannoma because the tumor is well encapsulated and the excision is relatively easy whereas the nonencapsulated form requires normal tissue margins to avoid relapse. Wide excision is not recommended because schwannoma rarely recurs after surgery. If the nerve of origin is visualized, an attempt should be made to separate carefully to preserve function, although this is sometimes not possible [6]. In this presented case tumour mass was well encapsulated and surgical excision of lesion was performed under local anaesthesia which is also evident in postoperative x-ray orthopentomogram (Figure 5). The prognosis of schwannoma is very good as malignant transformation and recurrence are rare events [12]. No malignant transformation has been reported for intraosseous neurilemmoma till now [21]. In the presented case also patient was regularly followed up for one year and found to be normal with no recurrence.
Figure 5: Postoperative x-ray orthopentomogram after removal of tumor mass.

Conclusion

Schwannoma should be kept in mind when observing a tumor in the oral cavity. Any painless nodule in the head and neck region must include schwannoma and biopsy and histopathological examination should be done to carry out definitive preoperative diagnosis.

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