Table 1 Differential diagnosis of osteosclerosis in the spine

Bone infarction

• Typically serpiginous or patchy geographic appearances.

Sclerotic metastases

• May have known history of cancer (e.g. breast, prostate, gastric, neuroendocrine).

• The ‘Double Line Sign’ of hyperintense inner ring and hypointense outer ring is a classic feature.

• Usually solitary lesion, T1 isointense or hypointense compared to red marrow, and minimally brighter on T2/STIR.

• H-shaped vertebrae and absence of the spleen may be a clue to sickle cell anaemia as a cause.

• A ‘Halo sign’ of rim hyperintensity and marked enhancement are highly suggestive.

Chronic granulomatous infection

• Often also associated with longitudinal ligament oedema and enhancement, vertebral destruction and intraosseous, and epidural and paraspinal abscesses.

Myeloproliferative neoplasms

• Diffuse, homogenous T1 hypointense but with variable T2 hypo- or hyperintensity depending on phase of disease.

• In late myelofibrosis, depletion of haematopoietic elements results in markedly hypointense marrow appearances on all sequences.

Chronic recurrent multifocal osteomyelitis (CRMO)

• Typically children or young adults.

Sclerotic multiple myeloma

• Uncommon, occurring in 3% of myeloma cases. Appears hypointense on all sequences.

• Clavicle involvement is a characteristic finding.

• Clinical features may help with diagnosis. CRMO is associated with psoriasis, inflammatory bowel disease, or skin conditions including SAPHO syndrome.

• May be associated with POEMS syndrome—clinical or radiological features of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes may be present.

Bone islands

• Generally oval-shaped and spiculated, and orientated to long axis of bone.

Osteosarcoma

• Predominantly hypointense on all sequences (T1, T2, STIR).

• Lack bone marrow oedema, periostitis, soft tissue mass, or other aggressive features.

• Associated with large areas of new bone formation.

Lymphoma/leukaemia

• May present as a focal bone lesion or ‘ivory vertebra’ with diffuse T1 hypointense but homogenously T2 hyperintense appearances.

Lymphoma/leukaemia

• May present as a focal bone lesion or ‘ivory vertebra’ with diffuse T1 hypointense but homogenously T2 hyperintense appearances.

• Tumour extension into soft tissues is a common feature of lymphoma.

• Tumour extension into soft tissues is a common feature of lymphoma.

• Leukaemia more typically presents as a diffuse process rather than focal/multifocal lesion, with diffuse slight T1 hypointensity and T2 hyperintensity appearance compared to the intervertebral disks.

• Leukaemia more typically presents as a diffuse process rather than focal/multifocal lesion, with diffuse slight T1 hypointensity and T2 hyperintensity appearance compared to the intervertebral disks.

Osteoid osteoma

• Usually under 30 years of age.

Mastocytosis

• Variable appearances—may be both lytic and sclerotic, diffuse, or focal.

• A T1 isointense and T2 hyperintense nidus is usually present in the neural arch.

• Typically T1 hypointense with mixed T2 and STIR signal intensity and multifocal or diffuse enhancement.

• Clinical history is often helpful: severe pain and scoliosis, improving with non-steroidal anti-inflammatory analgesics.

• Multifocal bubbly lesions may be identified.

Osteoblastoma

• Usually under 30 years of age.

Renal osteodystrophy

• The ‘Rugger-Jersey’ appearances of T1 and T2 hypointensity along the endplates are classic findings.

• Similar appearances to osteoid osteoma but larger (2–6 cm) and with more aggressive features (local growth and distant metastases).

• Renal atrophy, scarring, renal cysts, or lipomatosis may also provide clues to the underlying aetiology.

Giant cell tumour

• Usually young to middle-aged patient.

Paget’s disease

• Demonstrate fibrofatty change, trabecular disorganisation, and cortical involvement and expansion.

• More common in sacrum than elsewhere in the spine.

• Usually located in the vertebral body rather than neural arch, and has heterogenous, isointense T1 signal with enhancement.

• Variable T2 appearances depending on the stage of disease.

• The ‘Picture-Frame’ vertebra is a classic appearance at the mixed phase of disease.

• Areas of T1 hyperintensity may be present from intralesional haemorrhage.

• Fluid-fluid levels may be present if associated with an underlying aneurysmal bone cyst.

Fibrous dysplasia

• Appears T1 isointense to hypointense and T2 hypointense. Typically a well-marginated lesion with cortical thickening, and often with a clear halo of perilesional fat on T1.

Osteopetrosis

• Diffuse T1 and T2 hypointensity with vertebral thickening and spinal canal stenosis.

• The ‘Sandwich Vertebra’ appearance is a classic description.

Pyknodysostosis

• Patients often have a known history.

• Associated with short stature and scoliosis.