Which finding is often seen in peripheral blood smears of patients with multiple myeloma?

Rouleaux formation is a characteristic finding in the peripheral blood smears of patients with multiple myeloma. This phenomenon occurs when red blood cells stack together in formed shapes resembling a stack of coins. It is attributed to the increased plasma proteins, particularly immunoglobulins, which reduce the repulsive forces between red blood cells. In multiple myeloma, the overproduction of monoclonal immunoglobulins leads to an increased viscosity of the blood and subsequently causes this formation.

The presence of rouleaux can also contribute to the clinical symptoms of multiple myeloma, such as anemia and increased risk of thrombosis, as it may affect blood flow. This feature helps differentiate multiple myeloma from other hematologic conditions and is an important aspect of understanding the pathophysiology of the disease.