Hematopathology is a subspecialty of pathology which studies diseases of hematopoietic cells which originate from the bone marrow and contribute the cellular components of blood including red blood cells white blood cells and platelets. Hematopathologists most frequently evaluate peripheral blood smears, bone marrow aspirates, and lymph nodes biopsies to determine the nature of hematopoietic disease. The hematopathologist incorporates traditional microscopy with ancillary techniques including general laboratory values, immunohistochemistry, flow cytometry, and molecular diagnostic tests to make the most accurate diagnosis.