Examination of the blood and marrow are mainstays of hematologic diagnosis. The decision to perform a marrow examination, and the types of special studies required, should follow from a careful analysis of blood cells and the history and physical examination of the patient. Currently available automated blood cell analyzers provide an increasing array of novel quantitative parameters and flag abnormal samples that need manual microscopic review. The marrow should be examined when the clinical history, blood cell counts, blood film, or laboratory test results suggest the possibility of a primary or secondary hematologic disorder for which morphologic analysis or special studies of the marrow would aid in the diagnosis. In addition to determining the cellularity and morphology of precursor cells, or infiltration by nonhematopoietic cells, the marrow aspirate and biopsy provide cells for immunophenotyping by flow cytometry or immunostains, cytogenetic and molecular studies, culture of infectious organisms, and storage for further analysis.
Acronyms and Abbreviations
AML, acute myeloid leukemia; CHr, reticulocyte-specific hemoglobin content; CD, cluster of differentiation; CLL, chronic lymphocytic leukemia; EDTA, ethylenediaminetetraacetic acid; fl, femtoliter; FISH, fluorescence in situ hybridization; FLAER, fluorescently labeled inactive variant of the bacterial protein aerolysin; GPI, glycosylphosphatidylinositol; Hct, hematocrit; Ig, immunoglobulin; MCH, mean cell hemoglobin; MCHC, mean cell hemoglobin concentration; MCV, mean cell volume; MDS, myelodysplastic syndrome; M:E, myeloid-to-erythroid cell ratio; MPV, mean platelet volume; MRD, minimal/measurable residual disease; MYH9, myosin heavy chain 9; NK, natural killer; PCR, polymerase chain reaction; PDW, platelet volume distribution width; RBC, red blood cell; RDW, red cell distribution width; RET-He, reticulocyte-specific hemoglobin content; SD, standard deviation.
The blood and marrow are examined so as to answer these questions: Is the marrow producing appropriate numbers of mature cells in the major hematopoietic lineages? Is the development of each hematopoietic lineage qualitatively normal? Are there abnormal (eg, leukemia or lymphoma) cells present?
When it comes to the blood, quantitative measures available from automated cell counters are reliable and provide a rapid and cost-effective way to screen for primary or secondary disturbances of hematopoiesis. Light microscopic observation of the blood film is essential to confirm certain quantitative results and to investigate qualitatively abnormal differentiation of the hematopoietic lineages. Based on examination of the blood, the physician is directed toward a more focused assessment of marrow function or to systemic disorders that secondarily involve the hematopoietic system. At that point, a marrow examination may be pursued in order to explore marrow disorders as etiologies for blood abnormalities.
In 1923, Arinkin devised the marrow aspiration technique,1 which was the prototype for our current aspiration procedure. Regular use of the posterior iliac crest for aspiration and biopsy and regular use of biopsy to complement aspiration did not occur until the 1970s, when staging of lymphoma made biopsy a frequent procedure and new simpler biopsy instruments became readily available.
QUANTITATIVE MEASURES OF CELLS IN THE BLOOD