schwannoma is a benign tumor arising from neuroectodermal schwann cell of cranial , intraspinal , peripheral and autonomic nerve sheaths .
lesions in head and neck region account for 25 - 45% of extra - cranial schwannomas .
however , it rarely involves infra - orbital nerve and are uncommon in the maxillary and buccal space .
these tumors usually present as slow growing nodular mass and can mimic any benign growth in the head and neck .
the treatment of extra - cranial head and neck schwannomas is surgical and the approach depends on the location and extent of the tumor and the nerve involved .
this paper describes a case of schwannoma arising from infra - orbital nerve , presenting as slow growing nodular swelling in the buccal space .
the lesion was approached through skin incision and completely resected . at the time of exploration ,
the lesion was observed to emanate from the nerve trunk of peripheral branch of infra - orbital nerve , which was dissected and preserved .
only nine cases of infra - orbital nerve schwannoma are previously reported , which we discuss in relation to our experience .
a 40-year - old male patient presented with a chief complaint of painless swelling over left side of face .
the patient first noticed the swelling about a year back , which had grown gradually to its present size .
patient also complained of mid paresthesia over left cheek since past few months . on examination ,
a localized , nontender , firm , round swelling of about 4 cm was evident over left side of mid - face , extending from below the infra - orbital margin to upper lip [ figure 1 ] .
the skin was pinch - able over the lesion , except at the center of the lesion .
the overall clinical presentation was suggestive of a benign sub - cutaneous lesion and differential diagnosis included lipoma , fibroma , dermoid cyst , epidermoid cyst and neurogenic tumor .
lesion presenting as large sub - cutaneous nodular swelling ultrasonography was advised to study nature , size and extent of the lesion .
the ultrasonogram showed well - defined , heterogeneous oval mass of 45 mm  30 mm  23 mm within the buccal sub - cutaneous tissue with no orbital , maxillary sinus or underlying bone involvement [ figure 2 ] .
aspiration biopsy of the lesion showed spindle shaped cells predominantly arranged in antoni a pattern around verocay bodies , with less organized antoni b tissue in few places [ figure 3 ] .
diagnosis of schwannoma , probably arising from terminal branch of infra - orbital nerve was established .
ultrasonogram showing a heterogeneous oval mass within the sub - cutaneous tissue h and e stained section of aspirate showing verocay bodies ( arrow head ) surrounded by spindle shaped cells arranged in orderly parallel fashion ( arrows ) surgical excision of the lesion was planned and executed under local anesthesia . after attaining adequate anesthesia , linear incision of about 3 cm
the lesion was well - encapsulated , and freed from surrounding tissue by blunt dissection [ figure 4a ] .
portion of skin overlying the center of the lesion appeared thinned and was included in the excised nodule . at the time of exploration ,
the lesion was found to emanate from the nerve trunk of peripheral branch of infra - orbital nerve , which was dissected and preserved [ figure 4b ] .
( a ) exposure of the lesion through skin incision ; ( b ) dissected tumor attached to the nerve trunk of peripleral branch of infra - orbital nerve ( block arrow ) h and e stained section ( 10 ) of excised specimen showing spindle shaped cells predominantly arranged in antoni a pattern around verocay bodies ( black arrow ) , with less organized antoni b tissue in few places ( red arrow ) .
vessel in schwannoma having wide lumen , fibrotic wall and adjacent hyalinization ( blue arrow )
schwannoma ( neurinoma , peripheral glioma , perineural fibriblastoma and neurilemmoma ) is ectodermal benign neoplasm , which originates from schwann cell of cranial , intraspinal , peripheral and autonomic nerve sheaths .
they are common in head and neck region , accounting for 25 - 45% of extra - cranial schwannomas and 1 - 8% of all head and neck tumors .
it can involve any of the 12 cranial nerves , except the olfactory and optic nerves since they lack schwann cells in their sheaths .
schwannoma arising from infra - orbital nerve ( branch of maxillary division of fifth cranial nerve ) is extremely rare .
to best of our knowledge , only nine cases of infra - orbital schwannoma has been previously described in english literature .
depending on the site of nerve trunk or branch from which it arises , it may be located within the lower part of orbit , maxillary sinus or present as sub - cutaneous mass in infra - orbital region [ table 1 ] .
intraorbital schwannoma generally develop from supraorbital or supratrochlear nerves , and less frequently from infra - orbital nerves .
lesions arising from infra - orbital nerve grow to involve surrounding structures such as maxillary sinus , nasal cavity , infratemporal fossa and pterygopalatine fossa . however , it is rare to find schwannoma in the paranasal sinus , especially in the maxillary sinus .
swelling in the cheek , nasal atresia , downward transversion of the palate and pain , rarely accompanying exophthalmosis are common symptoms . however in our case , a well - localized painless infra - orbital sub - cutaneous swelling was observed without any ocular lesions or involvement of underlying osseous skeleton .
review of previously reported cases of schwannoma involving ion * rarely schwannomas may present with numbness in the distribution of involved nerve or with pain .
our patient reported paresthesia localized over area of distribution of superior labial branch of infra - orbital nerve , which was probably due to pressure or direct involvement of the peripheral branch of the nerve .
however during the surgical dissection , lesion was found to emanate from the nerve trunk of peripheral branch of infra - orbital nerve , which was dissected and preserved .
none of the previous cases of infra - orbital schwannoma reported preoperative paresthesia [ table 1 ] .
fine - needle aspiration cytology ( fnac ) , ultrasonography , magnetic resonance imaging and computed tomography image are diagnostic tools for schwannoma .
diagnosis using fnac is characterized by the presence of spindle cells and has only 17.6% accuracy .
aspiration of our lesion yielded blood tinged aspirate , which showed spindle shaped cells predominantly arranged in antoni a pattern around verocay bodies , with less organized antoni b tissue in few places confirming the diagnosis of schwanomma .
the treatment of schwannomas is exclusively surgical and the appropriate approach is dictated by the extent and location of the tumor . in our case ,
the tumor originated from the peripheral branch of infra - orbital nerve and presented as nodular swelling immediately underlying the skin .
incision placed in the natural skin crease of naso - labial fold was used to approach and completely remove the lesion .
other approaches used include intra - oral vestibular incision for smaller lesions localized in the buccal space , caldwell - luc approach for tumor within the maxillary sinus , subcilliary or eyelid crease incision for intraorbital schwannoma .
larger lesion involving greater areas of mid - face are treated by extra - oral weber - furgusson incision combined with ostectomy [ table 1 ] .
although malignant transformation and recurrence of schwannoma is very low , a case of recurrent infra - orbital schwannoma attributed to incomplete removal of the lesion through a limited skin incision was reported .
schwannoma arising from the infra - orbital nerve is rare , making the clinical diagnosis often difficult .
although uncommon , schwannoma involving the peripheral branch of infra - orbital nerve may present as localized mid - face swelling and should be included in differential diagnosis of benign sub - cutaneous swelling in infra - orbital region .
 extra - cranial schwannomas although common in head and neck region are very rarely seen originating from the infra - orbital nerve . 
 we report a case of schwannoma arising from infra - orbital nerve in a 40-year - old male patient . 
 the case presented as an isolated , asymptomatic , slow growing sub - cutaneous nodular swelling over left side of mid - face . on ultrasonography , 
 a localized lesion within the sub - cutaneous tissue of cheek was observed , without involvement of orbital , maxillary sinus or underlying bone . 
 aspiration biopsy of the lesion showed spindle shaped cells predominantly arranged in antoni a pattern around verocay bodies , with less organized antoni b tissue in few places . 
 diagnosis of schwannoma , probably arising from terminal branch of infra - orbital nerve was established . 
 the tumor was approached through skin incision . at the time of exploration , 
 the lesion was found to emanate from the nerve trunk of peripheral branch of infra - orbital nerve , which was dissected and preserved . 
 we correlate our experience with previously reported cases of infra - orbital nerve schwannoma . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSION