2012/12/27 12:27

Bone tumors

BONE TUMORS
It is important to distinguish between tumors of bone and tumors in bone, as the most commonly seen tumors in bone are not derived from bone cells such as osteoblasts and osteoclasts, but are either:
  • Bloodborne metastases of malignant tumors spread from other primary sites; or
  • Tumors of hemopoietic cells located within the marrow spaces of bones, particularly myeloma.

Myeloma is a tumor of plasma cells that commonly presents as single or multiple bone tumors

The vast majority of plasma-cell tumors occur in bone, arising in one of three patterns: diffuse plasma-cell infiltration of marrow, in which there is no discrete tumor formation; solitary osteolytic bone lesion (solitary plasmacytoma), which is an unusual pattern; and multiple osteolytic lesions in many bones (multiple myelomatosis).

Bone pain (and occasional pathological fracture) is an important clinical feature of myeloma. However, symptoms are not confined to bone because the neoplastic plasma cells produce abnormal amounts of immunoglobulin (usually IgG); this is of a single clonal type (monoclonal gammopathy), as it is produced by a single clone of neoplastic plasma cells. Many of the clinical features of myeloma are the result of the replacement of normal marrow cells by malignant plasma cells, together with the impact of the abnormal IgG (and its component heavy and light chains) on blood viscosity and renal function.

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