Paget‘s disease as important potential pitfall in 18F-PSMA PET/CT for prostate cancer

Description:

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.

 

References

1. Perera M., Papa N., Christidis D., et al. Sensitivity, specificity, and predictors of positive 68Ga-prostate-specific membrane antigen positron emission tomography in advanced prostate cancer: a systematic review and meta-analysis. European Urology. 2016;70(6):926–937. doi: 10.1016/j.eururo.2016.06.021.

2. Pyka T., Okamoto S., Dahlbender M., et al. Comparison of bone scintigraphy and 68Ga-PSMA PET for skeletal staging in prostate cancer. European Journal of Nuclear Medicine and Molecular Imaging. 2016;43(12):2114–2121. doi: 10.1007/s00259-016-3435-0.

3. Artigas C., Alexiou J., Garcia C., et al. Paget bone disease demonstrated on 68Ga-PSMA ligand PET/CT. European Journal of Nuclear Medicine and Molecular Imaging. 2016;43(1):195–196. doi: 10.1007/s00259-015-3236-x.

 

This Case was kindly provided by:

Matthias P. Fabritius
Department of Radiology
University Hospital, LMU Munich
Marchioninistrasse 15
81377 Munich
Germany
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