What unique formation of red blood cells, associated with multiple myeloma, resembles stacks of coins?

The formation of red blood cells that resembles stacks of coins is known as Rouleaux formation. This phenomenon occurs when red blood cells undergo a stacking arrangement due to increased plasma proteins, often seen in conditions like multiple myeloma. In multiple myeloma, the increased level of monoclonal proteins in the blood causes a change in the viscosity and surface charge of red blood cells, leading them to adhere to one another and form these characteristic stacks.

This accumulation can affect blood flow properties and may be observed under a microscope. Rouleaux formation is an important clinical indicator and helps in the diagnostic process of conditions associated with elevated immunoglobulins, making it a relevant finding in multiple myeloma patients.

Other terms such as agglutination refer to the clumping of red blood cells that can occur due to antibodies, spherocytosis describes a condition where red blood cells are shaped like spheres instead of the normal biconcave form, and echinocytosis is the presence of red blood cells with spiky projections. While these conditions involve changes in red blood cell morphology, they do not demonstrate the coin-like stacking characteristic seen in Rouleaux formation.