Answer of January 2012

Clinical History:

A 40-year-old lady with good past health presented with acute lower back pain precipitated by an accidental fall. On examination she had no loss of limb power or sphincter dysfunction, and was afebrile. Complete blood count and inflammatory markers were normal. CT and MRI scans were performed. 

Diagnosis:

Giant cell tumour of the vertebral body with secondary aneurysmal bone cyst

Discussion:

Giant cell tumours (GCTs) mainly presents in the second and fourth decades of life with a peak in the third decade, with a higher incidence in Asians and a mild female predilection.   Most GCTs are found in the end of long bones, mostly about the knee joint.  The vast majority are solitary lesions, with multiple lesions being associated with underlying Paget's disease.

Spinal GCTs are rare, accounting for only 2.7% of all GCTs in a review by Shankman et al. Clinical symptoms are most commonly pain (often with a radicular distribution), weakness and sensory deficits.  Most spinal GCTs affect the sacrum, followed by the thoracic, cervical and lumbar segments in decreasing order of frequency.

Most spinal GCTs involve the anterior elements, with occasional extension into the posterior elements.  Lesions purely involving the posterior elements are rare. Secondary aneurysmal bone cyst is present in 14% of cases. Differential diagnosis of an expansile lytic lesion involving the anterior elements of the spine mostly comprises aggressive/malignant entities, such as metastasis, lymphoma, chordoma, myeloma and plasmacytoma.  Plasmacytoma and myeloma are more commonly associated with posterior extension into the neural arch.  Chordomas have a predilection for the sacral spine, where they are calcified 90% of the time.  Eosinophilic granuloma is also on the list of differentials in a younger patient.  However, MR imaging is a useful modality for narrowing the list of differential diagnoses, as most other lesions in this list of differential diagnoses have high signal intensity on T2-weighted images (uncomplicated GCTs commonly show low to intermediate signal intensity on T2-weighted MRI.  The heterogeneous high signal in this case was due to trauma-related oedema).

Complete resection remains the treatment of choice for spinal giant cell tumours. Spinal GCTs have a higher rate of recurrence than peripheral GCTs, particularly in the sacrum, where tumours are larger and more difficult to extirpate. Radiation therapy remains controversial.