we present a case of a 57-year - old woman patient with a history of mid - aortic syndrome , treated with several vascular procedures , who was referred for investigation of metastatic disease of an undifferentiated sarcoma of unknown origin . positron emission tomography / computed tomography ( pet / ct ) demonstrated multiple fluorodeoxyglucose ( f - fdg ) avid lung , liver , and osseous metastases as well as a focus of increased f - fdg uptake in the area of the stented left renal artery . histologic evaluation of soft tissue from the region of the left renal artery revealed atypical spindle cells , consistent with an intimal sarcoma , and with histopathological characteristics identical to those of lung metastases , indicating the f - fdg avid lesion in the area of the renal artery as the origin of the metastatic disease . this case highlights the capacity of f - fdg pet / ct to detect primary tumors even of small size and in unusual localisations . moreover , it provides further indications regarding the potential association between foreign body reaction on the basis of chronic inflammation and sarcoma development . intimal sarcomas are very rare malignant mesenchymal tumors arising in large arterial blood vessels with a poor prognosis . the association between intimal sarcoma development and chronic foreign body reaction due to vascular prosthesis has been described . fluorodeoxyglucose ( f - fdg ) positron emission tomography / computed tomography ( pet / ct ) is an imaging modality with high negative predictive value and specificity in detecting adult soft tissue sarcoma . however , few reports have indicated the capacity of f - fdg pet / ct to detect intimal sarcoma in different sites . herein , we present a case of an intimal sarcoma arising in the site of a multiple stented renal artery detected with f - fdg pet / ct . a 57-year - old woman patient with a history of mid - aortic syndrome , treated with several vascular procedures of the aorta and the renal arteries underwent chest computed tomography ( ct ) due to dyspnea . histologic evaluation of a lung lesion , excised for diagnostic purposes , showed atypical spindle cells , consistent with metastases of an undifferentiated sarcoma of unknown origin . the patient was then referred to our department for f - fdg pet / ct for further investigation . f - fdg pet / ct demonstrated increased tracer uptake in the lung metastases as well as several f - fdg avid lesions in the liver and the pelvis skeleton compatible with multisystemic involvement of the metastatic disease . no evidence of a definite primary tumor was demonstrated with the exception of a focus of increased f - fdg uptake in the area of the stented left renal artery , higher than expected in a usual foreign body reaction due to vascular prosthesis ( fig . histopathological evaluation of soft tissue from the left renal artery revealed a perivascular area with atypical spindle cells consistent with an intimal sarcoma , and with histopathological characteristics identical to those of the lung metastasis , indicating the f - fdg avid lesion in the area of the stented renal artery as the origin of the metastatic disease ( fig . transaxial f - fdg pet / ct at the level of the abdominal aorta branching in the left renal artery ( a ) , the lungs ( b ) , the liver ( c ) , and the pelvis ( d ) . focally increased f - fdg uptake in the region of the stented left renal artery ( arrow ) , with higher f - fdg accumulation than expected in a usual foreign body reaction , proved to be an intimal sarcoma . physiological , diffuse tracer uptake in the abdominal aortic graft , compatible with foreign - body reaction due to aortic graft replacement 1 year ago on the ground of mid - aortic syndrome ( a ) . f - fdg positive lung metastasis in the left lower lobe ( arrow ) ( b ) . multiple f - fdg avid metastases in the liver ( arrow ) ( c ) . focal f - fdg accumulation in an osseous metastasis in the right post acetabulum ( arrow ) ( d ) . f - fdg  =  fluorodeoxyglucose , pet / ct  =  positron emission tomography / computed tomography . histologic image of the tissue in the area of the left renal artery stained with hematoxylin and eosin ( he stain ) , showing an infiltration of atypical spindle cells around a vessel - like structure ( a ) . ( b ) magnification of the atypical spindle cells . histologic image of the lung wedge resection ( he stain ) with a centrally necrotic metastasis of a sarcoma without evidence of a specific lineage differentiation ( c ) . the patient written informed consent was waived due to the retrospective nature of the presented case . intimal sarcomas are very rare , malignant mesenchymal tumors of large arterial blood vessels with an often unspecific clinical presentation and a poor prognosis . intimal sarcomas have been reported to arise in association with vascular prostheses suggesting a tumor inducing effect of foreign material on the endothelium . in this case report the development of an intimal sarcoma in a multiple stented renal artery due to mid - aortic syndrome is presented . to our knowledge , no case from intimal sarcoma in the area of the renal artery with a history of stenting has been described using f - fdg pet / ct . although a direct causal relation can not be proven , this case provides further indications regarding the potential association between sarcoma development and chronic foreign body reaction due to vascular prosthesis . vascular prostheses show physiologically increased f - fdg uptake in the graft material , even years after surgery without having a graft infection , most likely on the basis of a chronic inflammation proven to take place on the surface of such material . this knowledge could erroneously lead us to the assumption that the increased tracer uptake in the area of the stented renal artery is a foreign - body reaction manifestation . therefore , caution is suggested in the interpretation of foreign body reaction in f - fdg pet in patients with cancer of unknown primary origin and a history of repeated vascular prostheses .
abstractbackground : we present a case of a 57-year - old woman patient with a history of mid - aortic syndrome , treated with several vascular procedures , who was referred for investigation of metastatic disease of an undifferentiated sarcoma of unknown origin.methods:positron emission tomography / computed tomography ( pet / ct ) demonstrated multiple fluorodeoxyglucose ( 18f - fdg ) avid lung , liver , and osseous metastases as well as a focus of increased 18f - fdg uptake in the area of the stented left renal artery.result:histologic evaluation of soft tissue from the region of the left renal artery revealed atypical spindle cells , consistent with an intimal sarcoma , and with histopathological characteristics identical to those of lung metastases , indicating the 18f - fdg avid lesion in the area of the renal artery as the origin of the metastatic disease.conclusion:this case highlights the capacity of 18f - fdg pet / ct to detect primary tumors even of small size and in unusual localisations . 
 moreover , it provides further indications regarding the potential association between foreign body reaction on the basis of chronic inflammation and sarcoma development .