super scan  is a well described phenomenon on skeletal scintigraphy which is characterized by high skeletal to soft tissue ratio , uniform symmetrically increased bone uptake , and absent renal visualization . sye , et al . hypothesized that diseased bone shows increased uptake of radiopharmaceutical leading to reduced phosphate excretion and production of faint renal images on bone scan . we report a case of f-18 fluorodeoxyglucose ( fdg ) positron emission tomography ( pet ) super scan which shows features akin to super scan of skeletal scintigraphy and resolution of these features following initial phase of chemotherapy . a twelve - year old male presented with multiple joint pains , periorbital and sternal swellings of one - month duration . contrast - enhanced computed tomography ( ct ) scan of the abdomen revealed poorly enhancing , hypodense bilateral renal masses ranging from 4 cm to 5 cm in size along with multiple hepatic and pancreatic space occupying lesions . a 4.3-cm exophytic mass was noted in the lower pole of right kidney [ figure 1 ] . ct - guided biopsy from this mass revealed feature of renal primitive neuroectodermal tumor ( pnet)/ewing 's sarcoma [ figure 2 ] . contrast - enhanced computed tomography scan of the abdomen revealed poorly enhancing , hypodense bilateral renal masses ranging from 4 cm to 5 cm in size along with multiple hepatic and pancreatic space occupying lesions . a 4.3-cm exophytic mass was noted in the lower pole of right kidney histology of renal biopsy specimen from the lesion ( h and e staining , 10 ) showing sheets of malignant small round blue cells . ( a ) on immunohistochemistry , the tumor cells show strong and complete membranous positivity for mic-2 . ( c ) tumor cells were also negative for other markers in the round cell panel namely cytokeratin , leukocyte - common antigen , desmin , and synaptophysin ( not shown here ) . the findings are those of primitive neuroectodermal tumor / ewing 's sarcoma of the kidney thereafter , patient underwent a  true whole body pet scan including bilateral limbs and skull region as per the standard institution protocol for pre - treatment staging of the disease . the images revealed extensive hypermetabolic areas in ct described renal ( suvmax : 6.9 ) , hepatic ( suvmax : 7.2 ) , and pancreatic lesions ( suvmax : 5.4 ) . in addition , intense and non - uniform uptake was seen in marrows of axial and appendicular skeletal system with distinct focus in palpable sternal swelling ( suvmax : 4.5 ) . a medium - sized focus was also seen in left posterior chest wall with extension into basal pleura of left lung . interestingly , low background tracer concentration was observed along with very low f-18 fdg uptake in the brain ( suvmax of 3.3 in occipital region and 2.9 in rest of the brain ) , skeletal muscles of limb , mediastinum , and bowel . due to its resemblance with super scan of skeletal scintigraphy , these scan findings can be termed to represent  pet super scan  [ figure 3 ] . true  whole body pet scan including bilateral limbs and skull region shows extensive hypermetabolic areas in computed tomography described renal ( suvmax : 6.9 ) , hepatic ( suvmax : 7.2 ) , and pancreatic lesions ( suvmax : 5.4 ) . intense and non - uniform uptake was seen in marrows of axial and appendicular skeletal system with distinct focus in palpable sternal swelling ( suvmax : 4.5 ) and in left posterior chest wall with extension into basal pleura of left lung . scan shows low background tracer concentration with very low f-18 fdg uptake in the brain ( suvmax of 3.3 in occipital region and 2.9 in rest of the brain ) , skeletal muscles of limb , mediastinum , and bowel . due to its resemblance with super scan of skeletal scintigraphy patient was subjected to six cycles of euro - ewing 99 protocol including vincristine , ifosfamide , doxorubicin , and etoposide chemotherapeutic regimen as per the institution protocol . repeat pet scans were done after three and six cycles , latter being done after 4 months of the initial scan [ figure 4a ] . the images revealed marked treatment response with disappearance of  super scan-like pattern , reduction in number , size , and metabolic activity of the lesions that were shown in the earlier scan . suvmax of the occipital region of the brain increased from the previous value of 3.3 to 9.9 . for rest of the brain , the suvmax increased from 2.9 to 8.6 [ figure 4b ] . the comparison of femoral marrow activity in the pre- and post - treatment scans showed hypermetabolic areas of stimulation in post - treatment scan , which is clearly missing from the previously diseased marrow and gcsf - induced stimulated marrow being seen in previously uninvolved marrow . we have termed this pattern as  marrow flip flop  and it appears that areas showing marrow flip flop are the ones that demonstrate treatment response [ figure 4c ] . repeat pet scans were done after three and six cycles , latter being done after 4 months of the initial scan the images show marked treatment response with disappearance of  super scan-like pattern , reduction in number , size , and metabolic activity of the lesions that were shown in the earlier scan . suvmax of the occipital region of the brain increased from the previous value of 3.3 to 9.9 . for rest of the brain , the suvmax increased from 2.9 to 8.6 the comparison of femoral marrow activity in the pre- and posttreatment scans shows hypermetabolic areas of stimulation in post - treatment scan , which is clearly missing from the previously diseased marrow and g - cs - finduced stimulated marrow being seen in previously uninvolved marrow termed as  marrow flip flop it is an extremely rare malignant tumor with fewer than 50 cases in english literature . renal pnet is still rarer in children and adolescents age group with only four cases being reported in the pediatric age group.[57 ] to the best of our knowledge , we are reporting fifth such case . it usually presents in advance stage , behaves more aggressively than pnet at other sites , and usually shows poor response to the chemotherapy . similar characteristics of diffuse and intense hypermetabolism throughout the skeleton have been described in the earlier publications.[911 ] however , the scan in this case shows a very high contrast between the metastatic and non - metastatic organs with extremely low f-18 fdg uptake in brain , muscles of limbs , mediastinum , and bowel . unique feature of this case is demonstration of reversal of aforementioned f-18 fdg avidity after initial chemotherapy in the follow - up scan . another unusual feature of this case is the excellent chemotherapeutic response shown in this patient ; pnet of kidney is known to respond poorly to chemotherapy and a functional imaging modality may serve as a useful tool to demonstrate early response in such rare cases . marrow flip flop  could be due to involved marrow being replaced by fibrosis as a treatment response and hence would not demonstrate the marrow stimulation effect of colony - stimulating factors on a pet scan done to assess therapeutic response . in conclusion , though uncommon , the reporting physician should be aware of findings of  pet super scan  as demonstrated in this patient . reversal of these abnormalities on functional imaging following therapy guides the clinician to choose the best available regimen for this otherwise chemotherapy nave disease .
we report f-18 fluorodeoxyglucose ( fdg )  positron emission tomography ( pet ) super scan  akin to  super scan  of conventional skeletal scintigraphy , in a rare case of primitive neuroectodermal tumor ( pnet ) of the kidney . 
 a twelve year old male patient of metastatic pnet of the kidney was subjected to a  true 
 whole body f-18 fdg pet scan including lower limbs and skull region as per the institution protocol . 
 the images revealed extensive hypermetabolic areas corresponding to the computed tomography described renal , hepatic , and pancreatic lesions along with intense and non - uniform uptake in the marrows of axial and appendicular skeletal system . 
 interestingly , low background tracer concentration was observed along with very low f-18 fdg uptake in the brain , skeletal muscles of limb , mediastinum , and bowel . in view of these findings 
 , the scan can be interpreted as  pet super scan  due to its resemblance with the super scan of skeletal scintigraphy . a repeat f-18 fdg pet scan after chemotherapy revealed marked treatment response with disappearance of 
 super scan-like pattern , reduction in number , size , metabolic activity of the lesions , and stimulated marrow sans the previously diseased portion . 
 though uncommon , the reporting physician should be aware of  pet super scan  and its implications as described in this case .