Primary Tumors of the Sacrum: Imaging Findings.

The diagnosis of sacral neoplasms is often delayed because they tend to remain clinically silent for a long time. Imaging is useful at all stages of the management of sacral bone tumors, i.e., from the detection of the neoplasm to the long-term follow-up. Radiographs are recommended as the modality of choice to begin the imaging workup of a patient with known or suspected sacral pathology. More sensitive examinations, such as Computerized Tomography (CT), magnetic resonance (MRI), or scintigraphy, are often necessary. The morphological features of the lesions on CT and MRI help orientate the diagnosis. Although some imaging characteristics are helpful to limit the differential diagnosis, an imaging-guided biopsy is often ultimately required to establish a specific diagnosis. Imaging is of paramount importance even in the long-term follow-up, in order to assess any residual tumor when surgical resection remains incomplete, to assess the efficacy of adjuvant chemotherapy and radiotherapy, and to detect recurrence.