Final answer:
The most characteristic peripheral blood smear finding in multiple myeloma is the presence of monoclonal plasma cells with abnormal morphology and the presence of Russell bodies.
Step-by-step explanation:
The most characteristic peripheral blood smear finding in multiple myeloma is the presence of monoclonal plasma cells. In patients with multiple myeloma, there is an excessive division of lymphocytes producing abnormal immunoglobulins called M proteins. These M proteins can be detected in the blood and urine, and their presence can be observed on protein electrophoresis and immunoelectrophoresis tests.
On a peripheral blood smear, multiple myeloma may be suspected if there is an increased number of plasma cells and abnormal morphology, such as the presence of Russell bodies, which are globular accumulations of immunoglobulins within the cytoplasm of plasma cells. Additionally, bone marrow examination can provide further confirmation of the diagnosis.
So, to summarize, the most characteristic peripheral blood smear finding in multiple myeloma is the presence of monoclonal plasma cells, with abnormal morphology and the presence of Russell bodies.