Aravindha Babu, N. Anitha, U. Tamilarasi and S. Leena Sankari

Department of Oral Pathology, Sree Balaji Dental College and Hospital, Bharath University, Pallikaranai, Chennai - 600100.  

DOI : https://dx.doi.org/10.13005/bpj/1024

Abstract

Neural tumors are rare in the oral and maxillofacial region which occurs as both benign and malignant. They are neuroectodermal in origin. Most of the neural tumors arises from schwann cells and peripheral nerve sheaths. This paper reviews about the histological difference of the neural tumors of the oral region

Keywords

histological; malignant; neuroectodermal

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Copy the following to cite this article: Babu A, Anitha N, Tamilarasi U, Sankari S. L. Neural Tumors of Oral and Maxillofacial Region. Biomed Pharmacol J 2016;9(2).

Copy the following to cite this URL: Babu A, Anitha N, Tamilarasi U, Sankari S. L. Neural Tumors of Oral and Maxillofacial Region. Biomed Pharmacol J 2016;9(2). Available from: http://biomedpharmajournal.org/?p=8116

Introduction 

Nerve cells and supporting cells are the 2 main cells in the nervous system. Neuron or nerve cell is the main structural and functional unit of the system. Supporting cells of the CNS are neuralgia cells ,peripheral nervous system are schwann cells and satellite cells. Neural tumors are of neuroectodermal in origin. It appears as painless swelling which is of smooth surface in the soft tissues of the mouth. The most common site is being the tongue. In the head and neck region the most of the them are benign  tumors

Classification of neural tumors 

(WHO 1992 )

Benign Tumours

Traumatic Neuroma

Perineural Fibrosis

Neuromuscular HamartomaFibroblastoma, Neurinoma, Lemmoma

Nerve Sheath Ganglion

Schwannoma – plexiform , cellular , ancient or degenerated

Neurofibroma and Neurofibromatosis or Vonrecklingausen’ Disease Of Skin

Diffuse Neurofibroma

Pacinian Neurofibroma

Epitheloid Neurofibroma

Granular Cell Tumor

Melanocytic Schwannoma: Pigmented Schwannoma

Nerve Sheath Myxoma

Ectopic Meningioma.

Ganglioneuroma

Pigmented Neuroectodermal Tumor of Infancy

Malignant Tumours

Malignant peripheral nerve sheath tumors (MPNST).

Malignant Schwannoma

Neurofibrosarcoma

Malignant peripheral nerve sheath tumor with Rabhdomyosarcoma , glandular differentiation and Epitheloid

Malignant granular cell tumor

cellular cell sarcomas: Malignant melanoma of soft parts

Malignant melanocytic Schwannoma.

Neuroblastoma

Ganglioneuroblastoma

Neuropithelioma

Traumatic neuroma 

It occurs due to the trauma during  extraction of tooth , any physical injuries or at the site of previous injuries¹. Clinically  it appears as a swelling or small nodule near the mental foramen, lips or tongue. Traumatic neuroma of the mental foramen was first reported by cahn². Bone associated with nerve trunk may also occur. It is slow growing and becomes larger in size.

Histopathological appearance of traumatic neuroma of irregular mass with interlacing neurofibrils and schwann cells. Connective tissue is scanty and it is derived from perineurium. Proliferating nerve fibers may occur diffusely throughout the lesion or small discrete islands.³

Special stains used to identify collagen are the trichrome methods ( masson , Mallory)⁴. In IHC staining methods S100 and EMA appears to be positive for perineural components

Palisaded encapsulated neuroma 

It is benign true neoplasm. It cause primary hyperplasia of nerve fibers , axons and their sheath cells.⁵ clinically appears as a solitary , cutaneous tumor occurring mainly mucocutaneous junctions on the face. Oral cavity is rarest site of origin. Histopathological   appearance of neuroma shows encapsulated mass which may be complete or incomplete. Tumor consist of interlacing fascicles of spindle cells with moderately cellular and some have lobulated appearance. Special stains like schofield methos reveals the presence of numerous axons in the tumor. Differential diagnosis of the lesion is neurofibroma and neurilemoma^5,6.

Schwannoma (neurilemoma , perineural fibroblastoma  )  

It is a benign  neural neoplasm of nerve sheath origin. Schwann cells forms the inner layer of the peripheral nerve sheath. Head and neck region are most commonly affected. Bilateral or multiple  lesions is a feature of neurofibromatosis which is a hereditary condition⁵. Clinically it appears as solitary ,slow growing and pain may be associated in some lesions. In the head and neck region tumors occurs on both oral and paraoral region , in which tongue being the most commonly affected site^3,5. Intraosseous or central lesion affects both the maxilla and mandible. Pain , bone destruction and expansion of cortical plates may be seen in some of the lesions. The tumor is composed of 2 types of tissues Antoni A and Antoni B. Histopathological appearance of Antoni A shows spindle shaped cells with palisading arrangement and fibers are arranged in whorls or swirls. Verocay bodies are striking feature of the lesion. Antoni b does not exhibit a palisading arrangement and spindle cells are disorderly arranged. Microcyst formation is seen⁷. One of the histological variant of schwannoma is the ancient schwannoma (hemosiderin and hemorrahgic areas can be seen ) ⁸. Schwannoma cells are positive for S 100 protein and not for EMA

Neurofibroma 

It arises from both the schwann cells and perineural fibroblasts. Two forms of neurofibroma are solitary neurofibroma and neuro fibromatosis

Solitary neurofibroma 

It is a non encapsulated tumor of slow growing consisting of schwann cells and perineural cells. Neurofibroma is awell  demarcated lesion with proliferation of interlacing bundles of spindle cells ,wavy nuclei and sometimes melanocytes can be seen. Mast cells are the characteristic feature of the lesion which helps in diagnosis³. Solitary plexiform neurofibroma is a variant of neurofibroma which may be associated with neurofibromatosis and had a risk of malignant transformation³.

Neurofibromatosis (Von Recklinghausen’s Disease of Skin) 

it is a autosomal dominant condition with multiple neurofibromas , skin pigmentation and bony abnormalities which may transform into neurofibrosarcoma ⁵. Two types of neurofibromatosis are defined : NF type 1 – mutations on gene neurofibromin and NF type 2 – mutations on gene schwannomin. Clinical appearance shows café au`lait macules, Axillary freckling (Crowe sign), Iris freckling (Lisch spots) and  Bony changes  are also seen⁹.

 Malignant peripheral nerve sheath tumor ( neurogenic sarcoma , neurofibrosarcoma ) 

It arises from peripheral nerve schwann cells and its rare in the oral cavity. Sarcomas are of 2 types 1. Malignant transformation of neurofibromatosis to sarcoma¹⁰ 2. Malignancy in the absence of neurofibromatosis ¹¹. Malignant schwannoma commonly seen in lips, buccal mucosa and palate where as in central tumors mandible is more common. Histopathological appearance shows spindle shaped cells with comma shaped nuclei and cellular , nuclear pleomorphism , mitotic figures are very high. Schwannoma appears in 3 forms of pattern  1. Epitheloid 2. Rhabdomyoblastic differentiation 3. Glandular or mesenchymal ³.

Conclusion 

There is a chance of malignant transformation in benign tumors is seen so it is important to distinguish between the benign neoplasms and peripheral nerve neoplasms

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