a 35-year - old female presented with a painless , slowly growing 
 mass in the right inferior orbit for the past four years .
she did 
 not complain of diminution of visual acuity , diplopia or field 
 defect . on examination , visual acuity in both eyes
the right side demonstrated a solid , non - tender , 
 freely mobile mass in the inferior orbit , which became more 
 prominent on applying pressure on the upper part of the globe . 

the mass measured approximately 20 mm  15 mm and the 
 size did not vary with valsalva maneuver , ocular movements 
 or posture .
slit - lamp 
 and fundus examination of the eye showed normal anterior 
 and posterior segments .
b - scan ultrasonography revealed an extraconal , 
 homogenous lesion in the inferior part of the right orbit . 

computed tomography revealed a non - enhancing well- 
 defined homogenous mass measuring 20 mm  12 mm in the 
 right inferior orbit which was displacing the inferior rectus 
 and inferior oblique muscle upwards .
the mass was separate 
 from the above - mentioned muscles and produced no globe 
 indentation or displacement [ figure 1a ] .
a provisional diagnosis of orbital dermoid was made and 
 the patient was taken up for an excision biopsy .
peroperative findings were of a smooth , well - encapsulated 
 mass with no attachments to the surrounding muscles .
on histopathological examination , the gross specimen 
 consisted of a smooth well - encapsulated solid mass measuring 
 25 mm in the greatest diameter [ figure 1b ] .
microscopically , a 
 biphasic pattern of tumor cells was seen with areas of closely 
 packed spindle cells having fusiform nuclei and eosinophilic 
 cytoplasm ( antoni a ) admixed with looser myxoid tissue 
 having ovoid cells ( antoni b ) . at places ,
these tumors cells 
 were arranged in palisades and this arrangement of cells 
 is referred to as verocay bodies .
orbital 
 schwannoma is a tumor of adulthood usually presenting 
 between 20 to 70 years of age .
schwannomas are usually 
 asymptomatic when small and may produce progressive , 
 painless proptosis on enlargement
. a variable combination 
 of signs and symptoms may be present due to the variable 
 origin and location of the tumor in the orbit.2 displacement 
 of the globe is related to the site of the tumor mass .
most 
 schwannomas arise from branches of either the supraorbital 
 or supratrochlear nerves and hence produce downward 
 displacement of the globe .
less commonly , the tumor may arise 
 from the infraorbital nerve and produce upward displacement 
 of globe .
larger tumors may produce diplopia , particularly 
 when they arise from the orbital portion of the third , fourth 
 or sixth nerve .
the growth of the tumor may 
 cause compression of the optic nerve with papilledema or 
 optic atrophy .
surgical excision is the treatment of choice and 
 the tumor should be removed intact at the earliest to prevent 
 compression of the optic nerve.3 incomplete excision can lead 
 to recurrence or even intracranial extension .
highly cellular 
 tumors have greater chance of recurrence and malignant 
 transformation . therefore an early treatment is indicated 
 to avoid the complications related to progressive growth of 
 the tumor . in our patient , we were successful in achieving 
 the above objectives with timely and complete excision of 
 the tumor .
orbital schwannoma arising from the infraorbital nerve 
 is rare and clinical diagnosis is often difficult .
extensive 
 literature search revealed only a few case reports of an orbital 
 schwannoma arising from the infraorbital nerve.4 - 10 our 
 patient presented with the tumor in this uncommon location . 

a solitary schwannoma , though rare , should be considered 
 as a preoperative differential diagnosis of a unilateral slow- 
 growing orbital mass in an adult and prompt management 
 is warranted to prevent development of vision - threatening 
 complications .
 a rare case of unilateral orbital schwannoma arising from the 
 infraorbital nerve is presented . 
 an excision biopsy with complete 
 removal of the mass in the inferior orbit was performed . 
 a 
 definitive diagnosis was made on histopathological examination . 
 
 the clinical and histological features of schwannoma are 
 discussed . a need for early removal of such tumors 
 is 
 recommended to prevent complications . 
Case Report
Discussion