both hodgkin and non - hodgkin lymphoma ( nhl ) can involve the bones . the involvement may be solitary or multi - focal . combined treatment with chemotherapy and radiation has good response with the majority of the low - risk patients surviving until 10 years . we present the role of 18 fluoride - fluorodeoxyglucose ( 18f - fdg ) positron emission tomography - computed tomography ( 18f - fdg pet - ct ) in an interesting case of primary diffuse large b cell lymphoma ( dlbcl ) of the tibia . a 53-year - old - male patient who presented with pain and swelling of the right lower limb was evaluated . a biopsy from the swelling revealed dlbcl . he was referred to our center for a whole body 18f - fdg pet - ct for initial staging . pretreatment 18f - fdg pet - ct of the thigh and leg showed intense metabolic activity in a large soft tissue mass arising from the proximal part of right tibia [ figure 1 ] . pretreatment 18 fluoride - fluorodeoxyglucose positron emission tomography - computed tomography ( pet - ct ) showing intense metabolically active soft tissue lesion noted involving the proximal part of right tibia ( coronal pet ( a ) , fused coronal pet ct ( b ) , sagittal pet ( d ) , sagittal fused pet ct ( e ) and maximum intensity projection ( mip ) lower limbs ( f ) ) . mip of the whole body fdg pet ( c ) showing no abnormal lymph nodes elsewhere in the body the patient underwent chemotherapy and local radiation to the involved site and was referred for an 18f - fdg pet - ct 3 months after the completion of treatment . posttreatment 18f - fdg pet - ct was normal with complete regression of previously noted abnormality [ figure 2 ] . posttreatment 18 fluoride - fluorodeoxyglucose positron emission tomography - computed tomography ( pet - ct ) showing complete resolution of metabolic activity in the proximal part of right tibia ( coronal pet ( a ) , fused coronal pet ct ( b ) , sagittal pet ( d ) , sagittal fused pet ct ( e ) and maximum intensity projection ( mip ) lower limbs ( f ) ) . mip of the whole body fdg pet ( c ) showing no abnormal lymph nodes elsewhere in the body . primary bone lymphomas represent approximately 5% of the extranodal lymphomas , majority of which are dlbcl . they can arise from any bone , but long bones ( femurs and tibiae ) are the common sites . 18f - fdg pet ct helps in identification of lymph nodal involvement and also differentiation of monostotic from polyostotic involvement by lymphoma . 18f - fdg pet - ct is beneficial in the response assessment and effectiveness of treatment . viable tumor lesions are difficult to be differentiate from bone fibrosis and remodeling using conventional modalities . 18f - fdg pet is also more sensitive than magnetic resonance imaging in identifying response . patients treated with combined modality versus single modality therapy were found to have a superior outcome , with a significantly better survival . the 5-year overall survival for patients treated with combined modality was 95% in one of the largest studies . reports on the utility of 18f - fdg pet - ct in primary bone lymphomas have also been published . role of 18f - fdg pet - ct in initial staging and response assessment in lymphomas has been well - established . this case reports adds to the existing knowledge that 18f - fdg pet - ct is a useful modality in assessment of primary bone lymphoma .
primary lymphoma of the bone is a rare clinical presentation constituting to < 1% of all lymphomas . 
 the long bones are usually involved . 
 combined treatment with chemotherapy and radiation offers long - term survival . 
 the authors present the role of 18 fluoride - fluorodeoxyglucose positron emission tomography - computerized tomography in initial staging and response assessment in a case of primary diffuse large b cell lymphoma of the tibia .