[Multiple myeloma: etiology, epidemiology, tumor biology and pathophysiology]

Normal plasma cells in the bone marrow are terminal cells secreting immunoglobulins, which die after a short life of one day. This failure presents a great contrast to myeloma cells, which proliferate and occupy the bone marrow and other tissues. Human myeloma cells originate from precursors that find the bone marrow an optimal microenvironment to differentiate into plasma cells. A bewildering array of biological abnormalities of myeloma cells are related to complicated clinicopathological aspects of multiple myeloma. These include molecular, cytogenetic and oncogenic changes, kinetic abnormalities, changes in homing receptors of myeloma cells, multi-drug resistance, abnormal cytokine levels, cytokine receptor dysfunction and abnormal enzyme activities.