In multiple myeloma (MM), skeletal events involve in decreasing order the spine, ribs, skull, pelvis and proximal long bones. In the spine, osteolytic lesions preferentially affect the vertebral body, sparing the pedicles, and CT scans show destruction of cancellous bone with relative integrity of cortical bone. At MR images three patterns of spine involvement have been described with the focal pattern being the most frequent followed by total marrow replacement and a variegated marrow replacement. A marked enhancement of the signal after gadolinium is typical of myeloma lesions. The pathogenesis of osteolytic lesions is the result of a local process due to production of several factors by plasmacells and surrounding bone marrow cells that eventually activate osteoclasts. The osteoclastic activation, in turn, induces other cytokine production that stimulates plasmacell growth, thus forming a vicious cycle. Many cytokines have been suggested as responsible for lytic lesions but recent studies have indicated that the scenario is dominated by three elements: RANK, RANKL, and OPG. It is the ratio RANKL/OPG that regulates induction and activity of osteoclasts while all the other cytokines involved in this process (IL-1β, TNFβ, TNFα, IL-6, HGF) eventually intervene inducing RANKL expression. It is not clear if plasmacells produce RANKL. In addition, another osteoclastogenic cytokine, MIP-1α, seems to have an independent capacity to activate osteoclasts. A quantitative defect of OPG has been demonstrated in multiple myeloma patients while the administration of recombinant OPG in murine models reduces osteolysis and osteoclasts number. In addition, it is known that in MM there is not only an increase in osteoclasts activity but also a suppression of new bone formation. This is responsible for the failure of bone scan in detecting osteolytic lesions in MM patients. The most useful methods for evaluating myeloma bone disease remains plain radiograph. However, several studies have demonstrated the superiority of MR imaging over plain radiographs in detecting osteolytic lesions but it is limited to the spine and pelvis. So, in patients with asymptomatic multiple myeloma, MR is useful to identify occult lytic lesions of the spine and can help distinguish those patients with stable disease from those with imminent complications such as fracture or disease progression. Another promising imaging technique in MM is the FDG PET. It appears to have a strong sensitivity for osteolytic lesions but its relative unavailability strongly limits its application. Surgical treatment of spinal lesions in MM has a limited role because fixation devices can fail due to adjacent bone disease. A new technique, vertebroplasty, is extending worldwide for the treatment of vertebral collapse. Radiotherapy can be employed low dose to provide pain relief or at higher dose for treatment of solitary plasmacytoma. However, the medical treatment of choice for MM bone disease is therapy with new generation bisphosphonates. Controlled studies have demonstrated that patients treated with these drugs had a significant decrease in bone pain, analgesic drug usage, and fractures together with a significant improvement of quality of life and survival compared with patients treated with placebo. Other rare tumors made by aberrant hematic vessels are known as hemangiomas and hemangiotheliomas. They are usually not aggressive, although the malignant counterparts are also known; in the latter case, a varying degree of malignancy may be present and there is a trend to relapse locally. Very often they are diagnosed following an occasional finding, as they present a typical radiological aspect. A radiotherapy approach is the standard therapy; however, more recently, vertebroplasty has been employed with success.
|Titolo:||Emangioma, plasmocitoma e mieloma multiplo del rachide|
|Data di pubblicazione:||2002|
|Appare nelle tipologie:||1.1 Articolo in rivista|