Imaging of Sacral Tumors

Betty Jean Manaster, MD, PhD, Travis Graham, MD


Neurosurg Focus. 2003;15(2) 

In This Article

Radiographic Demonstration of Sacral Lesions

Patients with sacral lesions often initially present clinically with low-back or buttock pain, and radiography is often the first imaging modality performed. Although this is entirely appropriate, it may provide the clinician with false reassurance because sacral lesions are often not detected on the initial x-ray film. The sacrum is difficult to evaluate fully on radiographs because it is often obscured by overlying stool or bowel gas. Furthermore, the sacrum does not have a distinctive trabecular pattern that can be assessed for disruption. Thus, sacral lesions may become quite large before they are detected on plain x-ray film, and diagnosis is sometimes delayed until either neurological symptoms or symptoms relating to compression of pelvic organs develop. There are, however, specific sacral structures that should be evaluated thoroughly to avoid a false-negative reading. The sacral foramina are paired, with distinct foraminal "struts" that should be seen.. The sacroiliac joint is oblique; both the anterior and posterior portions of the joint must be visualized bilaterally. Additionally, the posterior iliac wing should be seen distinctly through the sacral ala. If any of these structures is absent, a lytic lesion occupying the sacral ala should be considered. In some of our cases in which radiographs were obtained, the sacral lesion was initially not identified. The aforementioned features should be kept in mind to identify the lesion in each case.