What is it?
The bone represents the third site of metastatic localization after the lung and the liver. The spine is the most frequent site of secondary bone tumors. Metastasis represent 90% of the series, leaving the remaining 10% to primary tumors of the spine. Primary tumors of the spine are divided into benign and malignat. Benigns include osteoid osteoma, osteoblastoma, aneurysmal bone cyst, giant cell tumor. Osteoid osteoma and osteoblastoma are the most frequent histotypes. Malignant tumors include chondrosarcoma, chordoma, Ewing’s sarcoma and osteosarcoma. The latter represents the most common sarcoma and makes up 3 to 15 % of all primary spinal tumors. The most frequent histotypes of metastasis are: multiple myeloma, breast, prostate, thyroid, lung, bladder, renal, melanoma/colorectal. The thoracic spine is the most common site of involvements (70%), followed by the lumbar spine (20%) and the cervical spine with the sacrum (10%). The vertebral body is involved in 80% of cases with the posterior elements being affected in 20%. Most metastases are osteolytic (95%), breast and prostate have also osteoblastic variant.
Which are the symptoms?
Clinical presentation of tumor involvement of the spine consists of: pain, neurologic symptoms, mechanical instability and spinal defomity. There are three types of pain: local pain due to periosteal stretching or inflammation caused by tumor growth; radicular pain caused by nerve root impingement due to tumor compression; mechanical pain associated with vertebral collapse. Neurologic symptoms consist in sensitivity disorders, motor disorders and sphincter disorders. Mechanical instability due to spinal metastasis is an indication for surgical stabilation. The most common score to evaluate the stability of the spine is the spinal instbility neoplastic score (SINS); SINS component are: location (0-3), pain (0-3), bone lesion (0-2), radiographic spinal alignment (0-4), vertebral body collapse (0-3), posterolateral involvement of spinal elements (0-3). Metastatic spine lesions with a low SINS (0-6) are generally considered stable while high SINS (13-18) suggests instability that is likely to require surgical stabilation. Painful scoliosis in an adolescent is strongly suggestive of osteoid osteoma or osteoblastoma.
How is it diagnosed?
Diagnosis uses conventional radiology associated with biopsy. Radiography can detect whether the lesion is osteolitic or osteoblastic and highlight a pathological fracture of the vertebra, CT is usually performed in order to visualize the vessels and the vascularity of the tumor and of the reactive tissues. In bone tumors it shows the extent of the tumor in the vertebra, the extent of the tumor in the soft tissue compartments and extracompartmental spaces and its relatiomship with the vascular bundle and viscera. CT is superior to MRI in showing mineralized tissues. CT is also useful in demostrating the effect of radiation or chemotherapy or local recurrence after a spine resections. MRI is as useful as CT for the local study of vertebral injury. In general, MRI is superior to CT in studyng the soft tissues, the bone marrow and the spine. MRI is also essential in demostrating the effects of chemotherapy or radiation therapy and in monitoring local recurrences after surgery. Angiography shows pathological vascularity and selective arterial embolization has become an indispensable tool to reduce intraoperative bleeding. It is also important to highlight the presence of artery of adamkiewicz. Bone scan and PET are important to localize the lesion and to differentiate tumors from infectious diseases. Laboratory tests are important for a diagnosis of multiple myeloma (monoclonal protein), osteosarcoma (serum alkaline phosphatase) and Ewing’s sarcoma (lactate dehydrogenase). The indication and execution of the biopsy require knowledge of the clinico-imaging diagnostics, the pathology and the treatment of bone and soft tissue tumors. Because all the tissues potentially contaminated by tumorous cells should be widely included in the definitive surgical removal, the biopsy approach should be placed along the line of the incision which will be used for the surgery. The primary decision in planning the biopsy is whether to perform fine needle biopsy, trocar biopsy, incisional biopsy or excisional biopsy. Fine needle biopsy is the less traumatic and less likely to contaminate tissue planes. It has the highest incidence of false negative. It is mainly used in soft tissue tumors, in local recurrence or metastases, in screening between tumor and infection. Trocar biopsy though scarcely traumatic, it may occasionally cause hematoma with potential contamination of the tissue planes. It allows you to get more material to analyze than fine needle biopsy. The incidence of false negatives is low. Incisional biopsy is indicated in difficult cases, where a detailed histological study on large specimens and the procurement of material for special studies is desired, and in cases where fine needle, trocar biopsy has been unclear. Incisional biopsy must follow very precise rules and meticulous technique. Excisional biopsy can be considered only for conditions whose radiographic pattern is pathognomonic, for example osteoid osteoma. Also in this case one must follow precise rules and meticulous technique.
How is it treated?
The aim of the treatment of primary spine tumors is an en-block resection with the goal of “safe histological margins” of one or more levels depending on the extent of the tumor. Vertebral anterior reconstruction can be obtained with carbon or titanium cage filled with autologous and homologous bone strongly connected to a stable posterior stabilization system (screws and rods). The improvement of medical treatments (chemotherapy and/or radiotherapy) in the tretament of primary cancer has led to an increase in the average survival of the cancer patient with an increase in functional needs. This has led to treat vertebral metastatic lesions not only with palliative interventions but, in selected cases, with curative interventions previously prerogative only of primitive tumors. Palliative interventions include: stabilization and decompression for pain control, mechanical instability and prevention or treatment of neurological damage; vertebroplasty or thermalablation; curettage or corporectomy. The decision in these cases is often made by a multidisciplinary team (oncologist, radiotherapist, orthopedic) to evaluate the right choice for each patient.
Where do we treat it?
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