Primary angiosarcoma of the bone (PAB) is a particularly rare and aggressive form of malignancy in the spectrum of vascular tumours, and it accounts for less than 1% of sarcomas. This case of PAB, diagnosed thanks to FDG-PET/CT guided biopsy, is a paradigm of how powerful are clinical informations that can be derived by a F-FDG PET/CT, in view of negative or inconclusive imaging of conventional radiology, starting from the metabolic characterization of an equivocal finding, the possibility to drive the biopsy towards the most active site, the accurate total body staging, the stratification of prognosis and early therapy assessment.