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Lytic Osseous Metastases


KEY FACTS

Terminology

  • Spread of primary tumor to spine, where bone destruction exceeds bone production

Imaging

  • Multiple osteolytic lesions in spine

  • Compression fracture with bowing of posterior cortex, osteolysis extending into neural arch, extraosseous soft tissue

  • Lesion distribution proportional to red marrow (lumbar > thoracic > cervical)

  • Radiography requires 50-70% bone destruction and tumor size > 1 cm for detection

  • Bone scan can give false-negatives with aggressively lytic tumor or with very small lesions

Top Differential Diagnoses

  • Hematopoietic malignancy

  • Benign (osteoporotic) compression fracture

  • Schmorl node

  • Normal heterogeneous marrow

  • Spondylodiscitis

Pathology

  • Spine is most common site of osseous metastases

    • Spine metastases found in 5-10% of cancer patients

  • Common primaries causing osteolytic metastases

    • Breast, lung, renal most common

    • Other: Thyroid, GI tract, ovarian, melanoma

Clinical Issues

  • Pain: Progressive axial, referred, or radicular

    • Compression fractures common

  • Epidural tumor extension may cause neurologic dysfunction

    • Cord compression in 5% of adults with systemic cancers (70% solitary, 30% multiple sites)

Lateral radiograph shows osteolysis of the C2 neural arch
and superior margin of the C3 arch
.

Sagittal T1WI MR in the same patient shows a large soft tissue mass replacing the C2 arch
. There is also replacement of marrow in the C2 body and dens
. Subsequent work-up disclosed nonsmall cell lung carcinoma in the right upper lobe.

Axial NECT shows large thyroid carcinoma metastasis to the vertebral body and left facet/lamina of C3. There is a thin rim of expanded bone
partially surrounding the lesion. The extraosseous soft tissue mass is not clearly seen
on bone windows.

Axial contrast-enhanced CT at a slightly lower level shows enhancement of the mass
, typical of hypervascular tumors like thyroid carcinoma. The medial margin of the mass is in the spinal canal, effacing the thecal sac and likely contacting the cervical cord.

TERMINOLOGY

Synonyms

  • Osteolytic metastases

Definitions

  • Spread of primary tumor to spine, where bone destruction exceeds bone production

IMAGING

General Features

  • Best diagnostic clue

    • Multiple lytic lesions in spine

    • Compression fracture with bowing of posterior cortex, osteolysis extending into neural arch, extraosseous soft tissue

  • Location

    • Vertebral body and posterior elements

    • Lesion distribution proportional to red marrow (lumbar > thoracic > cervical)

  • Size

    • Any size

  • Morphology

    • Typically round (due to centrifugal growth) destruction of bone

Radiographic Findings

  • Radiography

    • Requires 50-70% bone destruction and tumor size > 1 cm for detection

      • –

        AP: Absent (“missing”) pedicle, ± paraspinous soft tissue mass

      • –

        Lateral: Destroyed posterior cortical line

    • Plain films detect level of neural compression < 25%

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