Glossary and Atlas of Blood Film Descriptors

Anisocytosis: red cells of unequal size. Reflected in increased RDW (Red cell Distribution Width.)

Band cell: the stage of neutrophil maturation immediately before full maturity. Named after the shape of its nucleus. Appears in the blood during infections, and other marrow 'stress'

Blast Cell: early committed marrow precursor of mature red and white cells. This cell accumulates in the marrow in acute leukemia, and may appear in the blood in large numbers.

Dimorphic Blood Film: two populations of red cells - one microcytic and the other normocytic. Seen in treated or transfused iron deficiency, and sideroblastic anemia

Erythroblast: any nucleated red cell precursor

Howell-Jolly bodies: round nuclear remnants within the red cells. Indicate splenectomy or hyposplenism

Hypersegmented neutrophils: a neutrophil with six or more lobes. Usually (but not inevitably) means vitamin B12 or folate deficiency

Hypochrom(as)ia: pale red cells. Always accompanied by microcytosis

Left Shift: the presence of slightly immature white cells (eg bands and metamyelocytes), suggesting infection

Leukoerythroblastic: the presence of erythroblasts and myelocytes (which are precursors of mature cells) in the blood. Often indicates marrow infiltration eg by secondary cancer, or fibrosis

Macrocytosis: large red cells

Microangiopathy: indicates mechanical damage to red cells with red cell fragments on the blood film

Microcytosis: small red cells

Metamyelocyte: the stage of neutrophil maturation immediately before the band cell. Appears in the blood during infections, and other marrow 'stress'

Myelocyte: a white cell precursor. A component of the 'leukoerythroblastic' blood film

Pancytopenia: a reduction in all the formed elements of the peripheral blood. May indicate marrow failure

Poikilocytosis: a traditional term for red cells of unequal shape

Polychromasia: grey coloured red cells on film, indicating presence of increased reticulocytes

Reticulocyte: an erythrocyte newly released from the bone marrow, identifiable by a network or 'reticulum' of RNA in its cytoplasm (a special stain is needed to show this). After about 24 h, this RNA disappears. An increased absolute number of reticulocytes indicates increased marrow erythropoiesis.

Rouleaux: red cells in stacks, as coins. Indicates high ESR, eg infection, myeloma, cancer, collagen disease etc.

Schistocyte: a red cell which has undergone mechanical damage - synonymous with red cell fragment

Spherocyte: a spherical red cell due to disproportionate membrane loss. Either inherited, or acquired from (usually) immune causes

Sickle cell: a crescent-shaped red cell characteristic of Sickle Cell Anemia

Target cell: red cell with central area of Hb giving the appearance of a target. Seen in many conditions, including hemoglobinopathy and liver disease

Additional Investigations

Serum iron: reduced in iron deficiency, and in infections, inflammations, and malignant disease.

Serum transferrin: (same thing as TIBC) raised in iron deficiency, but low in infections, inflammations and malignant disease

Serum ferritin: reflects total body iron stores, except in the presence of liver disease or acute inflammation

Serum vitamin B12: low in vitamin B12 deficiency. Commonly low in the elderly, and significance unclear, but should not be ignored

Serum and erythrocyte folate: use the serum folate as an index of deficiency. Theoretically erythrocyte folate is a more stable index of folate status, but in clinical practice the serum folate is as good

Direct and indirect bilirubin: the increased load of bilirubin from hemolysis is unconjugated (indirect) and does not appear in the urine. A raised indirect bilirubin indicates either an increased load of bilirubin, or hepatocellular dysfunction.

Serum haptoglobin: this is a heme binding protein. It mops up free heme in the circulation, and the complex is then cleared by the RE system. A low haptoglobin indicates hemolysis (of any cause), or liver cell failure (low synthesis).

Bone marrow aspirate and biopsy: this is used to diagnose primary hematological and marrow conditions eg leukemia, secondary cancer, myeloma etc.

Hemoglobin electrophoresis: used to diagnose hemoglobinopathy. A solution of hemoglobin is prepared from the red cells, and analysed by electrophoresis. Abnormal hemoglobins can be recognized by their characteristic position on the paper or gel.