osteosarcoma ( os ) is an aggressive primary bone malignancy with a high propensity for pulmonary and skeletal metastases . metastases at other sites are rare . unlike other malignancies such as carcinoma breast , colorectal , head and neck malignancies , lymphoma , and melanoma where the role of fluorine-18 fluorodeoxyglucose ( f-18 fdg ) positron emission tomography / computed tomography ( pet / ct ) for restaging evaluation is established , the role is yet , we wish to demonstrate the ability of f-18 fdg pet / ct scan to detect unusual sites of disease recurrence . a 26-year - old young gentleman , a diagnosed case of os of right femur was treated with neoadjuvant chemotherapy followed by wide excision of the mass with prosthesis insertion . the patient had a disease free interval of 6 years following which he presented with a lump over the anterior abdominal wall . fine - needle aspiration cytology of the lump was suggestive of disease recurrence [ figure 1 ] . restaging f-18 fdg pet / ct revealed metastatic deposit in right paraspinal muscle at the level of c1 vertebra , muscle deposit in right arm , subcutaneous nodules in anterior abdominal wall , right lateral chest wall , left arm , serosal deposit over ascending colon and pancreatic deposit in addition to the pulmonary and bone metastases . no evidence of active disease was noted in the periprosthetic region at the operated site [ figure 2 ] . the patient was started on metronomic chemotherapy . fine - needle aspiration cytology of the anterior abdominal wall lump - h and e stained slides revealed hypercellular smear showing markedly pleomorphic/ sarcomatous cells including giant cells amidst stroma consistent with osteogenic sarcoma ( 200 ) . insert : a large sarcomatous cell with a pleomorphic nucleus and moderate cytoplasm ( 100 ) maximum intensity projected image ( a ) revealed multiple foci of increased fluorodeoxyglucose uptake which on correlative fused axial images corresponded to subcutaneous anterior abdominal wall deposit ( b ) , muscle deposit in right arm ( c ) , pancreatic deposit ( d ) , serosal deposit over ascending colon ( e ) , sternal ( f ) , and pulmonary metastases ( g ) . osteosarcoma is the most common nonhematolymphoid primary bone tumor arising from malignant transformation of primitive mesenchymal cells that produce osteoid or immature new bone . the peak incidence is seen in the second decade of life with slight male preponderance . although it can affect any bone , it has a predilection for metaphyses of long bones . the 5-year overall survival rate for primary localized os is about 75% compared to 25 - 50% in cases with lung or bone metastases . tumor site , size , metastases at presentation , response to chemotherapy , and surgical remission are some of the known independent prognostic factors . however , recurrence after 5 years is very rare and seen only in 5% of cases . lungs and bones are the common sites of disease recurrence . the unusual sites of recurrence reported in english literature are kidney , brain , muscle , subcutaneous tissue , stomach , duodenum , and penis . patients with pulmonary recurrence have a better prognosis as compared to those with extrapulmonary involvement . fluorine-18 fdg pet / ct has established the role in staging , assessment of treatment response , and restaging of various malignancies . the whole body survey of f-18 fdg pet / ct provides a one - stop shop for evaluation of local disease as well as detecting sites of distant metastases . in a systematic review on the role of f-18 fdg pet / ct in staging and restaging of oss , quartuccio el at suggested that f-18 fdg - pet and pet / ct is superior to bone scintigraphy and conventional imaging methods in detecting bone metastases ; while spiral ct is superior to f-18 fdg - pet for detection of pulmonary metastases from os . they recommended that combination of f18-fdg pet / ct with conventional imaging methods is a valuable tool for staging and restaging of os . though os are known to recur at local site or involve the lungs and bone , rarely they can also involve unexpected soft tissue sites such as muscle , subcutaneous tissue , anterior abdominal wall , serosal , and pancreatic deposits , respectively , as exemplified by our case . detection of multiple atypical sites of recurrence of os on f-18 fdg pet / ct in a single patient after 6 years of disease free interval makes our case unique . this case further emphasizes the potential role of whole body f-18 fdg pet / ct imaging in restaging of os and provides an impetus to conduct further prospective multicenter trials to validate the role of f-18 fdg pet / ct in restaging of os . the present case underscores the ability of f-18 fdg pet / ct to detect unusual sites of recurrence .
osteosarcoma ( os ) is the most common nonhematolymphoid primary bone malignancy characterized by osteoid or new bone formation 
 . lungs and bones are the most common sites of metastases . 
 we report a case where unusual sites of the soft tissue recurrence from os were detected on restaging fluorine-18 fluorodeoxyglucose positron emission tomography / computed tomography scan done post 6 years of disease free interval .