Skip to content

Bone Mets

Most common cause of cancer pain.

Diagnosis

Sclerotic

  1. Prostate
  2. SCLC
  3. Carcinoid

Lytic

  1. RCC
  2. NSCLC
  3. Melanoma
  4. Thyroid
  5. Rectal
  6. Endometrium
  7. Ovary

Mixed

  1. Breast (most are lytic)
  2. Gastric
  3. Colon
  4. Cervical
  5. Testicular

Other stuff.

10-20% are solitary. Renal is most likely but DD is wide.

Radiology

50-70% of bone destruction needed pre visualisation on plain film.
Most mets start in medullary bone and invade cortex. Lesions starting in cortex are unusual but think of xxx.

CT is less sensitive than MR but can see the cortex clearly unlike MR.

MR has high S/S (0.91 / 0.95)
DIXON (frequency specific) Fat Only (FO) is better than standard T1WSE
and 20% reduction in OP compared with IP means BENIGN at 1.5T. T2 hyperintense signal halo around lesions is moderately specific for mets.

Pathological Fractures

"normal mechanical forces disrupt the structural integrity of abnormal bones"

CT / Plain film
- Focal osteolytic lesion at fracture.

MRI
- Focal low T1 signal and high T2 / STIR
- +/- Additional supporting features include cortical disruption, endosteal scalloping, paraosseous scalloping.

Benign (non-pathological) fractures have more ill-defined marrow signal with no bone destruction, mass or soft tissue components and will improve over time.

Vertebral Insufficiency Fracture vs Malignant Collapses.

VFF tend to have:
- Band of subchondral marrow signal parallel to the end plate. (low T1 vs variable T2/STIR)
- 'Fluid sign' = linear fluid signal parallel to end plate (only 5% of malignant.
- Normal marrow signal in rest of the vertebral body.
- Normal signal in the posterior elements.
- No increased signal on DWI.
- No paraosseous soft tissue mass.
- Enhancement of the abnormal marrow signal.
- Healing over time
- No mets elsewhere.

Malignant lesions tend to have:
- Total infiltration of the vertebral body (low T1)
- Convex bulging of the posterior vertebral wall cortex.
- Involvement of the posterior elements.
- Increased signal on DWI (not for sclerotic)
- Par-osseous soft tissue mass.
- Enhancement of both osseous and parosseous components.
- No healing with time.
- Metastatic deposits elsewhere.

Bone Lesion Differentials

Multiple

  • Osteopoikilosis
  • Melorheostosis
  • Mastocytosis
  • CRMO
  • Pagets
  • Skeletal granulomata

Single

  • Osteomyelitis
  • Eosinophilic granulomatosis.