Imaging features of primary and secondary malignant tumours of the sacrum

Malignant tumours of the sacrum may be primary or secondary. While sacral metastases are frequently encountered, a diagnostic dilemma can present when there is a single sacral bone tumour with no history or evidence of malignancy elsewhere in the body. Familiarity with the imaging features and clinical presentations of primary malignant bone tumours is helpful in narrowing the differential. This pictorial review will illustrate with both common and uncommon malignant sacral tumours CT, MRI and positron emission tomography/CT, highlighting the specific features of each.