Most often with breast, lung, kidney, thyroid, oro- & nasopharyngeal, GI tract, bladder, uterine, ovarian, melanoma, chordoma, & paraganglioma primaries

Hypointense on T1WI, hyperintense on T2WI & STIR; diffusely enhance

Cortex, particularly posteriorly, & pedicles are often destroyed, while intravertebral discs are usually spared

T1 hypointensity & T2 hyperintensity reflects marrow edema

CSF pulsation remodels sacral canal, which shows smooth enlargement

Follows CSF signal intensity; no neural elements are seen within cyst

Tarlov cyst is similar in etiology: Congenital dilatation of nerve root meningeal sleeve

Arise in midline

Most common locations: Sacrococcygeal > spheno-occipital > vertebral body

Hyperintense to discs on T2WI; internal septations, variable enhancement, often amorphous intratumoral calcium

Can have large soft tissue component

Involvement of adjacent vertebral bodies via transdiscal extension; may be epidural, perivertebral, & perineural extension

May involve epidural space with vertebral body extension & bone erosion

May be primarily osseous with bone destruction or “ivory vertebra” appearance

Appears slightly hyperdense on NECT & demonstrates homogeneous enhancement

Lytic expansile lesion in sacrum or a vertebral body with narrow zone of transition & usually non-sclerotic margins

Although internal matrix is absent, there may be residual bone trabeculae

Can coexist with an ABC

Radiologically & histologically identical to brown tumors, which occur in setting of hyperparathyroidism

Majority occur in 3rd to 5th decades

Bone scintigraphy detects only 10%; PET imaging is sensitive for monitoring treatment response, as MM lesions are metabolically active

Clinically, monoclonal gammopathy and Bence Jones proteinuria are present

Hypointense cortex & thickened trabeculae

Active phase: Fibrovascular marrow (T1 hypointense/T2 hyperintense)

Mixed phase: Fatty marrow (hyperintense on T1WI and T2WI)

Presacral cyst that is contiguous with thecal sac, protruding through an anterior osseous defect; widened sacral canal & neural foramina

No soft tissue mass, enhancement, or calcification, which are seen with sacrococcygeal teratomas

Neurenteric cyst is within spinal canal; may be associated with dysraphism & vertebral formation anomalies

Arise in neural arch & majority (75-90%) extend into vertebral body

Cortical thinning & focal cortical destruction are common

Fluid-fluid levels can be seen with telangiectatic osteogenic sarcoma as well as ABC

Majority of patients younger than 20 years

Renal cell carcinoma can also have a “soap bubble” expansile appearance

May be isolated or secondary to osteochondroma/enchondroma degeneration

50% of these lytic destructive lesions demonstrate a chondroid matrix with “rings and arcs”

Cortical disruption & extension into soft tissues

Often has an osteolytic, expansile appearance without periosteal reaction

Secondary osteosarcomas can occur after radiation treatment or may be sarcomatous transformation of Paget disease or other benign bone lesion