<prompt> Multiple myeloma is diagnosis by-24 hour urine proteinKidney biopsy10 plasmacytomaRouleaux formation in blood  <response>: Answer is option4, roulex formation in blood. Multiple myeloma Much rouleaux formation of the red cells is in this thick area of red cell distribution. This is pathologic rouleaux in contrast to normal stacking of red cells in a thick area of a normal blood smear. The background has a bluish tinge. Two small lymphocytes and one mature neutrophil are in the field. Multiple myeloma Blood - 50X The stacking of cells rouleaux formation facilitates the rate of red cell sedimentation, a phenomenon that may be seen on a peripheral smear. 