Thursday, April 19, 2007

rbc morphology

Acanthocytes are a subgroup of schistocytes consisting of small spherical cells with several finger-like projections from the RBC surface distributed in an irregular manner. The ends of the projections tend to be slightly thickened. Acanthocytes are typically found in large numbers in hereditary abetalipoproteinemia (Bassen-Kornsweig disease, Chapter 22), in moderate numbers in severe liver disease or in anorexia nervosa, and in small numbers in association with schistocytes of other types in other conditions.
Red blood cell crenation (echinocytes) are RBCs that appear normal except for uniform small triangular projections arranged in a uniform manner around the circumference of the cell, like the outer edge of a gearwheel. When most of the RBCs have this appearance, they are most commonly artifactual; but in lesser numbers they may be found in liver disease, renal disease, hyperlipidemia, and in some RBC enzymopathies.
Bite cells (degmacytes) are RBCs with a semicircular defect in one area of the outer edge. When present in significant number, bite cells are suggestive of hemolytic anemia due to an oxidizing agent (Heinz body anemia).
Sickle cells are crescent-shaped RBCs pointed at one or both ends found in some patients with homozygous sickle cell anemia (Chapter 5). Hemoglobin SC disease may sometimes display stubby sickled cells with a short thick bar protruding from the center that represents an Hb C crystal.
Elliptocytes (ovalocytes) are oval RBCs found in varying numbers in persons with congenital elliptocytosis and occasionally in small numbers in normal persons. When seen on edge, the cells may look somewhat like short rods and, rarely, may superficially resemble an atypical sickle cell.
Target cells consist of a peripheral ring and central disk of Hb. Target cells are found in large numbers in Hb C disease (Chapter 5) and in lesser numbers with certain other abnormal hemoglobins, in thalassemia, and in chronic liver disease.
Teardrop cells look like RBCs in which one side has been gently pulled out to a sharp point while the opposite side is still rounded. These cells are most characteristically associated with myeloid metaplasia (myelofibrosis, Chapter 7) but can also be present in lesser numbers in other myeloproliferative syndromes, such as chronic myelocytic leukemia.
Stomatocytes are RBCs that have a rectangular or slit-like central pallor configuration. This may be due to hereditary stomatocytosis or may be drug induced. A few stomatocytes may be found in normal persons and in a variety of diseases.
Rouleaux are RBCs partially adhering to each other with the overall appearance of a partially spread out stack of coins. The RBC central clear area is usually absent. This appearance is similar to that normally seen in the very thick areas of a peripheral blood smear. However, with rouleaux there are a moderate number of free single RBCs intermingled with the RBC stacks, whereas there are no free RBCs in thick areas of the smear. Considerable rouleaux formation suggests the possibility of abnormal serum proteins (such as the monoclonal proteins of multiple myeloma).
Red Blood Cell Inclusions (Fig. 2-1)
Basophilic stippling describes a moderate number of small dark blue dotlike structures scattered fairly uniformly throughout the hemoglobinated area of the RBC. Stippling is derived from nuclear remnants, so that the cell represents a reticulocyte and thus may be seen in many of the same conditions as polychromatophilic RBCs. However, stippling is especially associated with lead poisoning (Chapter 35).

Fig. 2-1 Abnormal RBC. A, normal RBC; B, spherocyte; C, target cell; D, elliptocyte; E, echinocyte; F, sickle cell; G, stomatocyte; H, acanthocyte; I, J, K, L, schistocytes; M, teardrop RBC; N, distorted RBC with Hb C crystal protruding; O, degmacyte; P, basophilic stippling; Q, pappenheimer bodies; R, howell-Jolly body.

Howell-Jolly bodies are small, round, blue-black inclusions that are considerably larger than basophilic stippling and ordinarily occur only one to an RBC. Howell-Jolly bodies may be present in any severe anemia but are more likely to be seen in severe hemolytic anemias and after splenectomy.
Pappenheimer bodies are small dark-staining granular inclusions that tend to occur in small numbers, are irregularly distributed, and often occur in small groups. They actually are hemosiderin granules that can be confirmed with ferricyanide iron stains. They are found after splenectomy, in some patients with sideroblastic anemias, and occasionally in patients with severe hemolytic anemia.
Three types of RBC inclusions cannot be seen with Wright's or Giemsa stain. All three require supravital staining techniques or other special procedures. Reticulocytes (discussed in detail later) are the stage in RBC maturation just before full maturity. Their number serves as an index of bone marrow RBC production. Hemoglobin H inclusions can sometimes be seen on a reticulocyte preparation as uniformly distributed small round dots somewhat resembling basophilic stippling but of slightly differing sizes. If a reticulocyte is affected, the Hb H inclusions coexist with the more irregular and more linear reticulum structures. Heinz bodies also require a special staining procedure and may need RBC pretreatment with a strong oxidizing agent such as phenylhydrazine. Heinz body formation is most often found in anemias due to RBC enzyme defects, "unstable" hemoglobins (Chapter 5), and certain uncommon hemoglobins such as hemoglobin Koln and Zurich. The Heinz bodies are small, scattered, dotlike structures of varying size in the RBC derived from denatured hemoglobin.

Dr.Hari kumar