fibrosarcoma is a tumor of mesenchymal cell origin that is composed of malignant fibroblasts in a collagenous background . it can occur as a soft tissue mass or as a primary or secondary bone tumor . the sarcomas as a group differ from malignant epithelial neoplasms by their typical occurrence in relatively younger persons . it is central , arising within the medullary canal or peripheral , arising from the periosteum . secondary fibrosarcoma of bone arises from a preexisting lesion or after radiotherapy to an area of bone or soft tissue . several inherited syndromes such as multiple neurofibromas may have a 10% risk over a lifetime of developing a malignant peripheral nerve sheath tumor or fibrosarcoma . fibrosarcoma also has been noted to arise from preexisting lesion such as fibrous dysplasia , chronic osteomyelitis , bone infarcts , paget 's disease and in previously irradiated areas of bone . clinically , fibrosarcomas most often present as slow - growing masses that may reach considerable size before they produce pain . histologically , well - differentiated fibrosarcomas consist of fascicles of spindle - shaped cells that classically form a  herringbone pattern . the cells often show little variation in size and shape although variable numbers of mitotic figures can usually be identified . in poorly differentiated tumors , the histological appearance of high - grade fibrosarcoma may be similar to other tumors such as malignant fibrous histiocytoma , liposarcoma or synovial sarcoma . the positive immunostaining for vimentin , together with negativity for muscular immunomarkers , helps in diagnosing fibrosarcoma . the treatment of choice is radical surgery ; radiation therapy and chemotherapy can be used in inoperable cases . a 22-year - old female came with the chief complaint of swelling over the left front side of the face since 4 months [ figure 1 ] . the patient gave a history of rapidly enlarging swelling which attained the present size of 3 cm  4 cm . extraorally , the swelling extended superoinferiorly from infraorbital margin to the upper lip and anteroposteriorly from midline to the corner of the mouth . intraorally , the swelling appeared to be arising from the labial vestibule extending up to the second premolar of the left side [ figure 2 ] . the buccal cortical plates were expanded but intact . there was displacement and grade ii mobility in relation to 21 , 22 and 24 . extraorally , a swelling was noticed on the left side of face intraorally , the swelling was seen involving the left canine and extending up to the second premolar the orthopantomography revealed unilocular radiolucency associated with 11 , 12 , 21 , 22 , 24 and root resorption in relation to 21 , 22 , 24 with missing 23 [ figure 3 ] . radiograph showing well - defined radiolucency and resorption of teeth informed consent was taken from the patient and surgical excision was done and the tissue was sent for the histopathological examination . the hematoxylin and eosin stained sections revealed the presence of parakeratinized stratified squamous epithelium overlying the connective tissue stroma . the cells were arranged in fascicular pattern with few areas showing herringbone pattern of arrangement [ figure 4 ] . the cells were dysplastic in nature with most of them showing cellular and nuclear pleomorphism . the lesional cells were separated from the overlying epithelium by a zone of connective tissue . [ figure 7 ] . under high power the typical herring bone pattern was seen [ figure 8 ] . based on the histological assessment , the final diagnosis of intermediate grade fibrosarcoma was made . photomicrograph showing the spindle cells arranged in herringbone pattern ( h&e stain , 40 ) lesional cells showing positivity for vimentin ( ihc stain , 200 ) few areas showing round cells ( h & e stain , 400 ) the lesional cells were separated from the overlying epithelium by a zone of connective tissue ( h&e stain , 40 ) dysplastic spindle cells arranged in herringbone pattern ( h&e stain , 200 ) this is a type of sarcoma that is predominantly found in the area around the bones or in soft tissue . in earlier studies of soft tissue neoplasm , this tumor has been greatly overdiagnosed and this diagnosis has been frequently applied to virtually any richly cellular , collagen - forming spindle - cell tumor including malignant fibrous histiocytoma , malignant peripheral nerve sheath tumor and a host of other sarcomatous and pseudosarcomatous lesions . it is a rare tumor , accounting for approximately 5% of all malignant intraosseous tumors and especially affects the long bones . of all the fibrosarcomas occurring in humans , only 0.05% occur in the head and neck region . of this , almost 23% is seen in the oral cavity . fibrosarcoma may arise as a primary tumor in any part of the jaws and may be classified as either peripheral ( periosteal ) or central ( endosteal ) type . secondary fibrosarcoma of the bone may be associated with fibrous dysplasia , paget 's disease , bone infarct or cyst and/or osteomyelitis ; it may also occur as a malignant transformation of giant - cell tumor of the bone or be induced by prior irradiation . clinically , in the oral cavity , the major symptoms are pain , swelling and sometimes loosening of the teeth and paresthesia . radiographically , an osteolytic lesion is usually present , with ill - defined borders ; however , fibrosarcoma of the jaws can not be distinguished from other destructive lesions of the bone . the cells are rather uniform and spindle - shaped and arranged in fascicles , often forming a herringbone pattern . histologically , the degree of differentiation of this neoplasm is variable , comparable to either a benign fibroma or an anaplastic tumor . therefore , care should be taken to distinguish it from other spindle - cell neoplasms . fibrosarcoma has got variable presentation due to variation in degree of cellularity , mitotic activity and pleomorphism which has led to the histological grading of the tumor . grade i ( well differentiated ) refers to tumors of uniform nuclear appearance with an appreciable amount of collagenous intercellular substance . in grade ii ( intermediate ) grade iii ( high ) tumors are anaplastic cellular growths often containing many giant cells and mitotic figures . histological grading is important , as it has direct correlation with the prognosis of tumor . occasionally , it is difficult to differentiate fibrosarcoma from other spindle - cell neoplasm . markers for muscle ( desmin and actin ) , macrophages ( cd68 ) , neural tissue ( s-100 , neuron specific enolase ) , melanoma ( hmb-450 ) and epithelial tissue ( cytokeratin , epithelial membrane antigen ) will be absent . wadhwan et al . in 2010 reported two cases of fibrosarcoma of maxilla which was diagnosed on the basis of herringbone pattern with positivity for vimentin . dhanavelu et al . in 2012 reported a case in a 73-year - old female patient . khanna et al . in 2014 reported a case of fibrosarcoma of maxilla with its extension into maxillary sinus . the overall 5 year survival rate for fibrosarcoma of bone has been reported to be between 28.7% and 34% . periosteal fibrosarcoma has a better prognosis than that of medullary origin , with 5 year survival rates of 52% and 27% , respectively . local recurrence is very common , but metastasis is rare and occurs mostly in lungs or to distant bones . fibrosarcoma of jaws are rare , detailed clinical , histological and immunohistochemical analysis is very important in such cases . dentists should be able to recognize the features of fibrosarcoma to propose appropriate investigations and help in treatment planning .