Vertebral metastatic disease must be included in any differential diagnosis of a bone lesion in a patient older than age 40.
Vertebral metastases are already present in 10% of newly diagnosed cancers. They are much more frequent in higher age groups (>50 years).
Vertebral lesions are very frequently asymptomatic in the setting of widespread metastatic disease, and are thus often found incidentally when imaging is performed for other resons (e.g. staging).
Lesions may become sympomatic due to bone pain, pathological compression fractures, or extension into spinal canal with cord compression and ensuing neurology.
The most common primary neoplasms to involved the vertebrae include:
- breast cancer
- lung cancer
- prostate cancer
- renal cell carinoma
- gastrointestinal tract malignancies
Metastases are eitehr osteoblastic versus osteolytic, however osteoid formation and mineralisation is of limited help in determining the primary tumour as some metastases may secrete osteoblast- and osteoclast-stimulating factors at the same time. New bone formation may also occur after chemotherapy or radiation therapy. Having said that some primaries more frequently result in sclerosis than others.
Primaries with predominantly osteoblastic metastases (sclerotic extradural bone lesions) include:
Primaries with predominantly osteolytic metastases, that may rarely become osteoblastic (mixed sclerotic and lytic extradural bone lesions)
Primaries with osteolytic metastases
Metastatic lesions can have virtually any appearance. They can mimic a benign lesion or an aggressive primary bone tumor. It can be difficult, if not impossible, to judge the origin of the tumor from the appearance of the metastatic focus, although some appearances are fairly characteristic.
Radiographs are useful as an overview but are insensitive to small lytic lesions and struggle to assess for compromise of the canal. As metastases have a predilection for involving the posterior vertebral body and pedicle, a missing pedicle (see: absent pedicle sign) is a useful and subtle sign to seek on AP films.
The appearance on CT will depend on the degree of mineralisation of the metastasis. The more common lytic metastases appear as regions of soft tissue attenuation with irregular margins. The mass may breach the cortex and result in compromise of the spinal canal.
Sclerotic lesions appear hyperdense and irregular but are less likely to extend beyond the vertebrae.
MRI is sensitive to metastatic disease and is able also assess for cord compression. The signal intensity of the metastatic deposits will vary according to the degree of mineralisation.
- T1: hypointense
- T2: hypointense
Mixed sclerotic and lytic extradural bone lesions
- T1: hypointense
- T2: hypo- and/or hyperintense
Lytic extradural bone lesions
- T1: intermediate to hypointense
- T2: hyper- or isointense
- T1 C+ (Gd): enhancement usually present
For osteoblastic metastases consider:
- bone islands (enostoses)
- spondylosclerosis hemispherica
- primary bone tumours (osteoblastoma, osteoid osteoma)
- therapy effects (radiation, chemotherapy, vertebroplasty)
(mostly solitary lesions, patients may however present with a history of cancer)
For mixed sclerotic and lytic extradural bone lesions consider:
- primary bone tumours
- therapy effects
For lytic extradural bone lesions consider:
- primary bone tumours
- aneurysmal bone cyst
- infective spondylitis
- atypical haemangioma
The differential diagnosis for bone tumours is dependant on the age of the patient, with a very different set of differentials for the paediatric patient.
- bone-forming tumours
- enchondromatosis (Ollier disease)
- Maffucci syndrome
- chondromyxoid fibroma
- fibrous bone lesions
- bone marrow tumours
- other bone tumours or tumour-like lesions
- skeletal metastases
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Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Metastasis - vertebral||✗|
|Vertebral body metastases||✗|