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the principal malignancy of peripheral nerve origin is preferably called a malignant peripheral nerve sheath tumor .
mpnst is also termed as spindle cell malignancy , neurilemmoma , neurogenic sarcoma , neurofibrosarcoma .
it is an extremely rare malignancy that is encountered in patients with neurofibromatosis type i with an incidence of 25% , while in the general population it has an incidence of 0.001% .
mpnsts are mainly located in the buttocks , thighs , brachial plexus and para - spinal region , and are rare in the head and neck region .
a female patient of age 23 years reported to the department of oral medicine and radiology with a chief complaint of pain and swelling in the lower right side of the jaw since 1 month .
past history revealed that the patient had visited a dentist 6 months back with a complaint of pain , swelling and mobility of teeth in the same region .
a panoramic radiograph was advised , and it showed a radiolucent lesion extending from the midline to the distal aspect of 46 . the patient was advised a minor surgical procedure during which extractions and incisional biopsy were performed .
the patient complained that there was recurrence of the swelling and pain in the same region since 1 month for which she was referred to our hospital .
the pain was sharp , intermittent and localized in nature , aggravating while eating food and getting relieved on taking medication .
the recurrent swelling was initially small in size and had attained the present size within 1 month . on general physical examination ,
on examination , an extra - oral swelling was seen on the right side of the mandible that was extending from the midline to the right ramus of the mandible , superior - inferiorly from the corner of the mouth to 5 cm below the inferior border of the mandible , crossing the midline of size measuring 5 cm  8 cm ; margins of the swelling were well defined .
on palpation , the swelling was hard in consistency , fixed to the underlying structures and tender .
i / o examination showed missing 31 , 32 , 41 , 42 , 43 , 44 , 45 and 46 and a diffuse swelling in the right of the alveolus measuring about 6 cm  2 cm , extending anteriorly from 31 to 47 posteriorly with obliteration of the buccal vestibule .
[ figure 1 ] based on the history , past history and clinical examination , recurrent fibrosarcoma was given on the right side .
a ) panoramic radiograph revealed irregular ragged borders on the right side of mandible , b ) extra oral swelling on the right side of mandible , c ) extra oral swelling involving submental region on right side , d ) intra orally a diffuse swelling seen on the right side of the alveolus further investigations were carried out .
panoramic , occlusal , cone beam computed tomography ( cbct ) , computed tomography ( ct ) and chest radiograph were advised .
the panoramic radiograph revealed irregular shaped radiolucency , ragged borders on the right side of the mandible extending from the distal aspect of 32 to the mesial socket of 48 , superoinferiorly from the crest of the ridge to the inferior border of the mandible , destruction of mental foramen and thinning of the inferior border of the mandible and missing 31 , 32 and 4147 .
the occlusal radiograph revealed pathologic fracture on the right side . to know the extent of the lesion , cbct was advised .
the cbct revealed few bone islands with complete destruction of both buccal and lingual cortical plates .
the ct scan revealed a large lobulated enhancing soft tissue density mass lesion measuring 5 cm  3.7 cm  6.3 cm seen on the body and ramus of the mandible , right buccal mucosa and gingivobuccal sulcus extending up to retromolar region .
few subcentimeter lymph nodes on the right side at level two were seen , with the largest measuring 6 mm  7 mm [ figure 2 ] . to know the metastasis ,
a ) panoramic radiograph revealing floating teeth appearance of 43.44 and 45 , b ) post operative panoramic radiograph revealing irregular , ragged borders on the lower right side of mandible , c ) ct scan revealing soft tissue density mass on the right side of mandible , d ) cbct revealed few bone islands with complete destruction of both buccal and lingual cortical plates the patient was subjected to incisional biopsy .
histopathology showed highly cellular connective tissue stroma composed of a mixed population of cells , predominantly spindle cells , arranged in streaming fascicles .
the tissue was strongly reactive for vimentin , [ figure 3 ] s-100 and nuclear specific enolase [ figure 3 ] and negative for cytokeratin and cd 34 ; hence , favoring the diagnosis for mpnst .
excision of the lesion was performed where hemimandibulectomy was performed and the specimen was sent for ihc investigation [ figure 4 ] .
the excision biopsy report confirmed the diagnosis of mpnst . compiling the information obtained by the radiological histopathological and ihc investigations , a final diagnosis of mpnst was arrived at .
a ) photomicrograph of h and e section showing spindle cells , b ) nse immunohistochemistry was positive , c ) s-100 stain , d ) vimentin stain post operative clinical photograph after hemimandibulectomy and radiation therapy with post operative panoramic radiograph
a sarcoma is defined as a mpnst when at least one of the following criteria is met : 
 it arises from a peripheral nerveit arises from a preexisting benign nerve sheath tumor ( neurofibroma)it demonstrates schwann cell differentiation on histologic examination . 
 
it arises from a peripheral nerve it arises from a preexisting benign nerve sheath tumor ( neurofibroma ) it demonstrates schwann cell differentiation on histologic examination .
mpnst is an uncommon sarcoma with an incidence of 1:100,000/year , compromising 510% of all soft tissue sarcomas ( sts ) .
mpnst originates from or recapitulates the phenotype of peripheral nerves cells , such as schwann cells or perineural cells .
although the histogenesis of mpnst remains unclear , there is a higher incidence in patients with prior radiation exposure and neurofibromatosis type 1 ( nf1 ) , who have a lifetime risk of 10% of developing mpnst .
mpnsts typically arise in the extremities ( 40% ) , followed by the trunk / retroperitoneal ( 38% ) and head and neck regions ( 21% ) .
most mpnsts are biologically high - grade sarcomas that tend to recur ( 4065% ) and metastasize ( 4080% ) .
most of the mpnsts occur in the age group of 2050 years , with an equal predilection to males and females .
usually , mpnsts are found in the extremities and the trunk and , unlike benign schwannomas , are seldom found in the head and neck area .
oral tumors may occur anywhere , but the most common sites are the mandible , lips , buccal mucosa , paranasal sinus , nasal cavity , orbit , cranial nerves , larynx , parapharngeal or pterygomaxillary space , minor salivary glands and the thyroid gland .
the present case comprises an extremely unique presentation of this malignancy involving the mandible on the right side in a 23-year - old female .
clinically , they present as an enlarging mass , often associated with pain and nerve deficit .
ct is useful in assessing the tumor extension and eventual metastasis ( the more frequent are bone and lung metastasis ) .
magnetic resonance imaging ( mri ) can reveal the nerve of origin , and it is more accurate to evaluate the topographical relationship of the tumor with the neighboring structures , especially the vascular and muscular structures and fat planes involvement . in particular , mri distinguishes the lesion from the fat tissue better than ct , whose dislocation and thinning of the fat tissue thickness has a critical importance in localizing the space of origin of a neck lesion .
fine needle aspiration , or fna , is a biopsy method employed to obtain individual cells for cytologic review .
it can be performed with a very small needle , which is more easily tolerated by the patient and is often useful to establish the presence of malignant cells .
a second type of biopsy is a core needle or tru - cut needle biopsy , which uses a larger hollow - bored needle gauge to obtain a more substantial tissue sample .
this type of sample offers inspection of both individual cells as well as the architectural arrangement of those cells within a given part of the tumor mass .
approximately 8085% of mpnsts are spindle cell tumors with fasciculating patterns that contain histologic features similar to those of a fibrosarcoma .
they are often high - grade , demonstrating four or more mitotic figures per high - powered field .
the remaining 15% of mpnsts is composed of tumors that exhibit variable differentiation , allowing them to be sub - classified as distinct entities .
a mpnst with rhabdomyoblastic differentiation is characterized by both neural and skeletal muscle differentiation . within this category
is the malignant triton tumor , which refers specifically to a mpnst occurring in association with rhabdomyosarcoma .
other examples of mpnsts with differentiation include glandular malignant schwannoma , epithelioid malignant schwannoma and superficial epithelioid mpnst . in 5070% of the mpnsts ,
s-100 positivity is not seen in other spindle cell sarcomas . also , some cases of mpnst stain positive for neuron - specific enolase . in our case of mpnst ,
the tissue was strongly and diffusely positive for vimentin , s-100 and neuron - specific enolase .
the goal of the operation is to achieve complete surgical excision of the tumor with negative ( wide ) margins .
treatment with adjuvant radiotherapy has yielded a statistically significant reduction in the rates of local disease recurrence .
studies have shown the average 5-year survival rate for these patients ranges from 16% to 52% .
mpnsts are very infrequent diseases of the head and neck region and in young patients without neurofibromatosis i syndrome . in our case ,
mpnst was seen in a young female patient involving the mandible without neurofibromatosis i syndrome , which is said to be rare as stated in the literature .
although a multimodality therapy , including surgical resection and adjuvant radiotherapy , is available , the prognosis remains dismal .
modern clinical studies and the development of effective targeted chemotherapy are needed to gain control of the disease .
malignant peripheral nerve sheath tumor ( mpnst ) of the mandible is an uncommon tumor that develops either from a preexisting neurofibroma or de novo . 
 mpnsts are sarcomas that originate from peripheral nerves or from cells associated with the nerve sheath , such as schwann cells , perineural cells or from fibroblasts . 
 because mpnsts can arise from multiple cell types , the overall appearance can vary greatly from one case to the next . 
 a case of mpnst of the right side of the mandible in a 23-year - old female is reported .