Intensity of FDG uptake is not everything: synchronous liposarcoma and fibrous dysplasia in the same patient on FDG PET-CT imaging.
A growing number of studies have demonstrated the usefulness of FDG PET-CT in the preoperative assessment of soft tissue sarcomas. We report a case of a patient with a known low-grade liposarcoma demonstrating only mild hypermetabolism on a FDG PET-CT study. An incidental osseous lesion was found in the distal tibia of the same extremity during the initial workup. This tibial lesion was significantly more intense on the FDG PET-CT study than the primary sarcoma. Further investigation showed this to be an unexpected benign fibrous dysplasia. We present this case as an example of the discrepancy of FDG activity, which may exist between truly malignant and benign lesions that may arise from soft tissue and osseous structures. A benign process should remain in the differential diagnosis for hypermetabolic lesions when evaluating a case of known malignancy, especially when the degree of uptake of that lesion differs significantly from that of the primary lesion.
Charest
Mathieu
M
Service of Nuclear Medicine, Lakeshore General Hospital, Montreal, Canada. charestm@myway.com
Singnurkar
Amit
A
Hickeson
Marc
M
Novales
J A
JA
Derbekyan
Vilma
V
D003952:Diagnostic Imaging / Q000379:methods; D005357:Fibrous Dysplasia of Bone / Q000175:diagnosis* / Q000473:pathology*; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology; D006801:Humans; D033162:Incidental Findings; D008080:Liposarcoma / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000494:pharmacology; D012509:Sarcoma / Q000175:diagnosis* / Q000473:pathology; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods*; D051598:Whole Body Imaging / Q000379:methods
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18