foreign body granulomas due to surgical swab left after surgery ( gossypiboma ) are rare . gossipyboma with radiological appearance of soft tissue sarcoma are rare and we report one such case 32 year old male laborer had fracture shaft femur 13 years back which went into malunion after conservative treatment . patient was asymptomatic for 10 years after which he presented to us with swelling and pain in the medial aspect of thigh . radiograph showed soft tissue mass with excavating lesion of the posteromedial aspect of femur resembling soft tissue sarcoma . complete removal of all granulomatous tissue was done and patient was given hip spica for 3 months after which he was gradually mobilized and is currently walking full weight bearing at one year follow up . cases with radiologically destructive lesions close to previous surgery scars should be assessed with gossypiboma as one of the differentials . gossypiboma is defined as foreign body ( surgical gauze ) surrounded by granulomatous reaction . the reported frequency of gossypiboma after surgery varies from 1 in 1000 to 1 in 10000 interventions   and this is rarely encountered in orthopaedic surgery and only few articles with lesion in thigh are published previously ( table 1 ) [ 3 - 10 ] . appearance of radiologically destructive lesion with bony involvement is rare and we report one such case . a 32 year old male reported to us with complaints of pain and swelling in right thigh for 3 years . the pain was moderate in intensity and was dull aching in nature , gradually increasing and aggravated on walking . 1a ) of femur 13 years back . open reduction and k nail fixation was done at that time ( fig.1b ) . post - operative course was uneventful and patient starting walking normally after physical examination the overlying skin was normal and oval non fluctuant swelling was present on posteromedial aspect of thigh approximately 10 cm by 10 cm . the swelling was soft , tender on deep palpation and present deep to the medial group of muscles of the thigh . the total and differential blood counts were essentially normal and esr was slightly raised ( 20mm / hr ) . radiograph of the right thigh showed increased soft tissue density over posteromedial aspect of upper third femur along with excavation of the posteromedial cortex of the femur ( fig . fine needle aspiration cytology ( fnac ) of the lesion was done and serosanginous fluid was aspirated which was sent for culture . a- plain radiograph ap view of the femur showing malunion at the age of 10 years . osteoclasis , open reduction and internal fixation with k nail was done at that time at another institution . c- the radiograph of the femur at the time of presentation showing marked erosion of the posteromedial cortex resembling sarcoma or osteomyelitis . ct - angiography of both the lower limbs was done earlier by a general surgeon . it showed normal blood flow in both the femoral arteries and there was no evidence of any vascular mass on the right side ( fig . 2 ) . patient did not agree for mri due to financial constraints . since th provisional diagnosis was either a chronic infection or a low grade malignancy a decision for surgical biopsy deeper to it , overlying posteromedial surface of bone was found to contain a malodorous , brown color necrotic mass consisting of shredded surgical swab around 7  77 cm . shredded gauge piece were removed piecemeal as it was completely adhered to adductor longus and medial hamstrings ( fig . on microscopy , cotton thread were visualized which were surrounded by chronic inflammatory cells forming foreign body granuloma ( fig . ct angiography was done at another centre to rule out vascular tumour like haemangioma but it was found to be normal . adductor muscles were carefully dissected . beneath the adductor muscle large cavity lined by fibrous tissue it was not possible to remove the gauze in single piece as it was completely shredded . post - operatively in view of excavated lesion in the femur , the patient was given hip spica for 3 months followed by gradual weight bearing . although with use of modern radiopaque markers in surgical gauze and change in practice of counting of gauze preoperatively and post operatively has decreased the number of cases of gossypiboma , still such cases could be found especially in developing countries where it is difficult to afford such surgical gauze with radiopaque marker . olnick et al   reported that that reaction of the body for retained surgical gauze could be of two types : either exudative or aseptic fibrous inflammatory response . the exudative response is more common and it leads to abscess formation with or without secondary bacterial contamination . aseptic fibrous inflammatory reaction is usually is rare and it develops into cyst formation with adhesion to the surrounding structures . only 6% are reported after orthopaedic surgery in comparison to 52% following abdominal surgery and no fatal complications have been reported in musculoskeletal sites . on radiograph it may show a soft tissue shadow or if calcified may show a whorl - like pattern . mri is the best modality to diagnose gossypiboma ; sugimura et al   reported that wavy low signal intensity lines on t2w imaging are characteristic findings of gossypiboma . in present case mri complications of the gossypiboma in musculoskeletal sites could be abscess formation , draining sinus formation , erosion of the underlying bone and pathological fracture . in cases reported in thigh the presentation varied from painful to painless swelling . radiographic picture was mostly of a destructive lesion and differential of chronic infection and low grade tumor was given in most studies . in our case too , the same differentials were entertained and we did not suspect gossypiboma in our differential . thus one of the learning points in this case report is to keep gossypiboma as a differential for slow growing destructive bony lesions in cases with previous surgeries at same site . in two cases , pathological fracture occurred   and in our case too we felt the bone was quite weakened . hence hip spica immobilization was given in our case to prevent the pathological fracture and was well tolerated by the patient with good result . the best way of preventing gossypiboma is by developing protocol at institutional level to write down the number of swabs preoperatively and post operatively with sterile marker pen by scrubbing nurse and tally it with senior surgeon and as far as possible swabs with radio opaque marker should be used . the conclusion of the above case report is that whenever such eroding lesion in femur after history of surgery is seen , we should keep pseudotumour due to surgical sponge ( gossypiboma ) as differential diagnosis . also it highlights the counting of sponges and use of radio opaque marker in sponges . radiographically this might appear as destructive bony lesions or with pathological fractures and can confuse with tumor or infection .
introduction : foreign body granulomas due to surgical swab left after surgery ( gossypiboma ) are rare . 
 there are few cases of such lesion after orthopaedic procedure in thigh . 
 presentations vary from pathological fracture to painless mass . 
 gossipyboma with radiological appearance of soft tissue sarcoma are rare and we report one such casecase report:32 year old male laborer had fracture shaft femur 13 years back which went into malunion after conservative treatment . 
 osteoclasis , open reduction and k - nailing was done at 6 months . 
 fracture united and k nail was removed 3 years later . 
 patient was asymptomatic for 10 years after which he presented to us with swelling and pain in the medial aspect of thigh . 
 radiograph showed soft tissue mass with excavating lesion of the posteromedial aspect of femur resembling soft tissue sarcoma . 
 biopsy revealed cystic lesion with sterile fluid with no malignant cells . 
 explorations of the lesion lead to discovery of shredded surgical swab . 
 complete removal of all granulomatous tissue was done and patient was given hip spica for 3 months after which he was gradually mobilized and is currently walking full weight bearing at one year follow up.conclusion:cases with radiologically destructive lesions close to previous surgery scars should be assessed with gossypiboma as one of the differentials .