Multiple myeloma and bone disease: pathogenesis and current therapeutic approaches.

Multiple myeloma is a haematologic malignancy caused by clonal expansion of malignant plasma cells and associated with bone disease and hypercalcaemia. Myeloma cells are in close proximity to sites of active bone resorption and the interactions between those cells, osteoblasts and osteoclasts, are crucial not only for the bone distraction but for the proliferation of bone marrow cells as well. Recent studies have revealed that numerous regulating factors of osteoblast and osteoclast activity interfere with the pathogenesis of multiple myeloma's bone disease and that the understanding of the pathophysiological pathways involved is the first step towards discovering novel potential therapeutic approaches.