… A high index of suspicion is crucial as an otherwise curable lesion can be rendered incurable if managed inappropriatelyCharles Fisher
Benign primary bone tumors of the spine
- Osteoid Osteoma
- Giant Cell Tumor (GCT)
- Aneurysmal Bone Cyst (ABC)
- Eosinophilic granuloma (EG)
Malignant primary bone tumors of the spine
- Ewing Sarcoma
- Malignant fibrous histiocytoma (MFH)
- Plasmocytoma/multiple Myeloma
- Peripheral Neuroectodermal tumor (PNET)
Primary spine tumors a relatively rare. They constitute about 4-13% of all primary bone neoplasms with an incidence of 2.5-8.5/100,000. The Thoracic spine is the most common location, likely due to the number of vertebrae. In general, it affects middle-aged patients. Osteoblastomas are the most common benign lesion, followed by ABC and then Osteoid Osteoma. Chordomas are the most common malignant tumors followed by osteosarcoma, then chondrosarcoma then Ewing’s sarcoma.
The presenting symptom is pain in 75% of cases. In general, three types of back pain can be distinguished. Mechanical, Neurologic, and Oncologic. Mechanical back pain is usually due to instability and results from tissue stretching. The patient is typically unable to mobilize and might show obvious deformity. Neurologic back pain is usually due to cord or root impingement. This pain could be activity mediated, usually associated with weakness, or numbness, and mot broadly with neurologic deficit. Oncologic pain is usually due to tissue stretch, microfracture and cytokine release from tumor tissue, it typically is a nighttime pain.
Imaging studies help generate a working diagnosis. Some patterns tend to be characteristic. For example, Giant cell tumors and Ewing’s sarcoma are lytic in nature. Osteosarcomas have aggressive bone formations with ill-defined borders. ABCs have a balloon-like pattern with double density content. Infiltrating erosions arising from the posterior wall are suggestive of Chordoma while soft tissue masses arising from the posterior elements with rounded calcifications are typical of chondrosarcomas. I recommend reviewing this radiopedia article for additional details.
Biopsies are essential to determine the diagnosis and eventual surgical plan. A biopsy is mandatory whenever there is suspicion of a primary bone tumor of the spine except in two scenarios:
- For certain benign tumors such as hemangioma, fibrous dysplasia, and exostosis, the imaging is typically pathognomic and these lesions can be followed at 4 or 6 months intervals
- In the case where the patient presents with acute neurologic deterioration, the surgeon faces the decision to stage the tumor and obtain a diagnosis or proceed with neurologic decompression that could potentially render the patient incurable due to violation of the tumor. It is often possible to delay the surgical treatment with the use of steroids. Ultimately the decision should be made with the patient’s input.
Staging of bone and soft tissue tumors was prposed in the 1980s by Enneking et al.
Three stages are proposed for benign tumors:
|Stage 1: Latent, Inactive||Asymptomatic lesions bordered by a sclerotic rim||Do Not grow or grow very slowly||Typically no treatment required|
|Stage 2: Active||Bordered by a thin capsule, bone scan positive||Grow slowly|
|Stage 3: Aggressive||Thin or absent capsule, bone scan highly positive||Rapidly growing||Curettage might be associated with a high rate of recurrence|