Enlarged Vertebral Body, Soap Bubble Expansion

Lubdha M. Shah, MD

DIFFERENTIAL DIAGNOSIS

Common

Metastases, Lytic Osseous
- Lung Carcinoma
- Thyroid Carcinoma
- Renal Cell Carcinoma
Multiple Myeloma
Osteoblastoma
Giant Cell Tumor
Aneurysmal Bone Cyst

Less Common

Chordoma
Chondrosarcoma

Rare but Important

Fibrous Dysplasia
Telangiectatic Osteosarcoma
Enchondroma
Angiosarcoma
Cystic Angiomatosis

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Zone of transition is helpful to assess aggressiveness
Multiplicity of lesions, soft tissue component, & vascularity of lesions can be helpful in narrowing the differential diagnosis

Helpful Clues for Common Diagnoses

Metastases, Lytic Osseous
- Lung, thyroid, renal, breast, oro-/nasopharyngeal carcinoma
  - Destructive lesion involving the posterior cortex & pedicle
  - Intervertebral discs are spared
  - Location proportionate to red marrow (lumbar > thoracic > cervical)
Multiple Myeloma
- Multifocal malignant proliferation of monoclonal plasma cells leads to heterogeneous T1 marrow signal
- May be expansile, but vertebral compression is more common
- Vertebral body more frequently involved
- Pedicle involvement later than with metastases
Osteoblastoma
- Ovoid expansile mass originating in the neural arch, often extend into the vertebral body
- 40% in spine
  - 40% cervical, 25% lumbar, 20% thoracic, 15-20% sacrum
- Florid edema (corona effect) suggests an aggressive process, attributable to prostaglandin release by the tumor
- Peritumoral edema enhances avidly with gadolinium administration
- Usually demonstrates more discrete bone matrix as compared to fibrous dysplasia
- Bone scan demonstrates avid radionuclide uptake by the tumor
Giant Cell Tumor
- Expansile, lytic lesion with narrow zone of transition
- ± Cortical breakthrough
- Centered in vertebral body
- Margin usually not sclerotic
- ± Residual bone trabeculae
Aneurysmal Bone Cyst
- Expansile lesion may show cortical breakthrough
- Shows a narrower zone of transition
- Centered in posterior elements
- Can be associated with fibrous dysplasia

Helpful Clues for Less Common Diagnoses

Chordoma
- Midline soft tissue mass with osseous destruction
- T2 hyperintense mass with multiple septa
- Can involve adjacent vertebral bodies by extension across disc space
- Arise from notochord remnants
Chondrosarcoma
- Lytic mass ± chondroid matrix, “rings & arcs”
- Cortical disruption
- Extension into soft tissues
- Nonenhancing areas: Hyaline cartilage, cystic mucoid tissue, necrosis
- Neural arch involved more frequently than vertebral body

Helpful Clues for Rare Diagnoses

Fibrous Dysplasia
- Well-defined, expansile, radiolucent lesion
- Neural arch involved more frequently than the vertebral body
- Spine involvement typically in polyostotic disease
- Fusiform bone expansion with “ground-glass” matrix
- Heterogeneous T1/T2 signal & heterogeneous enhancement
- Paraspinal soft tissue extension & vertebral collapse rare
- Prevalence of scoliosis in patients with polyostotic fibrous dysplasia & spinal lesions is reported between 40% and 52%
Telangiectatic Osteosarcoma
- Wide zone of transition with adjacent bone
- Permeative appearance & cortical disruption
- Multiple fluid-fluid levels
- Soft tissue mass ± mineralization
Enchondroma
- Expansile, homogeneous, slightly enhancing lesion with or without calcification
  - Arise either from migration of hyperplasitic immature spinal cartilage outside vertebral axis
  - Or from metaplasia of connective tissue in contact with the spine or annulus fibrosus
- Common benign cartilaginous tumour involving the acral skeleton but extremely rare in the vertebral column (2% of cases)
Angiosarcoma
- Lumbar region is most commonly affected
- 33% in axial skeleton
- Coarse trabecular/honeycomb pattern is suggestive of a vascular tumor
Cystic Angiomatosis
- Lytic, well-defined, round or oval lesions within the medullary cavity
- Intact cortex & variable peripheral sclerosis
- Endosteal scalloping & honeycombed or latticework appearance
- Discrete circular or serpentine lytic areas within bone suggest vascular channels
- No periosteal reaction

SELECTED REFERENCES

1. Leet AI et al: Fibrous dysplasia in the spine: prevalence of lesions and association with scoliosis. J Bone Joint Surg Am. 86-A(3):531-7, 2004

2. Murphey MD et al: From the archives of the AFIP. Musculoskeletal angiomatous lesions: radiologic-pathologic correlation. Radiographics. 15(4):893-917, 1995

3. Kumar R et al: Expansile bone lesions of the vertebra. Radiographics. 8(4):749-69, 1988

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