What is the red cell phenomenon in this blood smear from a patient with multiple myeloma?
The red cell phenomenon in this blood smear is rouleaux. The massive amount of serum immunoglobulin in patients with multiple myeloma interferes with the normal repellent force between red cells, allowing the cells to pile up on top of each other in formations that resemble stacks of coins. Rouleaux formation can also occur in hyperproteinemia due to other causes, such as chronic inflammation or hyperfibrinogenemia of pregnancy, and it usually occurs artifactually in the thick end of any blood smear.
-Kristine Krafts, MD, is an Assistant Professor of Pathology at the University of Minnesota School of Medicine and School of Dentistry and the founder of the educational website Pathology Student.