Uptake characteristics of fluorodeoxyglucose (FDG) in deep fibromatosis and abdominal desmoids: potential clinical role of FDG-PET in the management

In this preliminary report, we explore the uptake pattern of fluorodeoxyglucose (FDG) in fibromatosis and hypothesize the potential clinical role of FDG-positron emission tomography (PET) in the management of this benign but locally aggressive heterogeneous group of soft-tissue tumours. Five patients were studied (two men and three women, age range 23-35 years), among whom were three cases of deep musculoskeletal fibromatosis, one of abdominal fibromatosis (abdominal desmoid) associated with familial adenomatous polyposis (Gardner's syndrome) and one case of both deep musculoskeletal fibromatosis and abdominal desmoid. The FDG uptake in the lesions was heterogeneous in four cases and relatively homogeneous in one case. The uptake ranged from low to moderate grade with areas or foci of relatively avid FDG uptake. The maximum standardized uptake value (SUVmax) observed was up to 4.7; the avidity probably related to the biological aggressiveness and tendency for recurrence, characteristic of fibromatosis. A dual-point FDG-PET carried out over four active foci in two cases registered an increase in SUV ranging from 6.93% to 25.85% (mean 19.28%). Treatment monitoring with chemotherapy was carried out in two cases: the reduction in FDG uptake was consistent with the histological evidence of fibrosis and reduction in mitosis. Hence, a baseline FDG-PET can serve a valuable role in monitoring the effect of systemic pharmacotherapy in patients with recurrent progressive disease after unsuccessful local-regional treatment. The findings in this report can be extrapolated and have implications for studying the utility of FDG-PET in defining aggressiveness, guiding biopsy and defining excision site in a large tumour and in monitoring therapy in fibromatosis.