Paget‘s disease as important potential pitfall in 18F-PSMA PET/CT for prostate cancer
A 61 year-old male with history of resected Gleason 7 prostate cancer and radiotherapy presented with a slight PSA-increase from 0.26 to 0.48 in one year. Subsequent 18F-PSMA PET/CT scan showed two osseous metastases in the ribs with increased PSMA uptake. Furthermore a significantly increased PSMA expression was seen in the left os pubis and the entire left os ilium with extensive sclerosis on CT. Considering the relatively low PSA value and size constancy over 3 years as well as independence of further PSA course (decrease after radiotherapy of ribs), this finding is most compatible with Paget’s disease.
Sensitivity and specificity of PSMA PET/CT for bone involvement in patients with prostate cancer is about 99-100% and 88–100%, respectively. In view of these high sensitivity and specificity values, false-positive findings may create diagnostic pitfalls. Endothelial expression of PSMA in neovasculature known to occur in Paget disease has been postulated as the mechanism causing the PSMA PET/CT positivity of this condition.
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This Case was kindly provided by:
Matthias P. Fabritius
Department of Radiology
University Hospital, LMU Munich