Multiple myeloma (MM) is a malignant tumor of plasma cell characterized by overproduction of abnormal plasma cells in the bone marrow and skeletal destruction. The clinical features are bone pain, renal impairment, immunodeficiency, anemia and presence of abnormal immunoglobulins (Ig).

Increased amount of stacking of erythrocytes into long chains. Rouleaux (singular: rouleau) is derived from a French word that can refer to a stack of coins put into a cylindircal paper roll. Rouleaux formation is observed with increased serum proteins, particularly fibrinogen and globulins, and represents the cause of increased erythrocte sedimentation rate because rouleaux sediment more readily than isolated red blood cells.