RED BLOOD CELL MORPHOLOGY
Abnormal size is called anisocytosis (aniso means unequal). Abnormal shape is called poikilocytosis (poikilo means various). Elliptocytes may be seen in hereditary elliptocytosis. Spherocytes result from decreased erythrocyte membrane, and they may be seen in hereditary spherocytosis and in autoimmune hemolytic anemia. Target cells result from increased erythrocyte membrane, and they may be seen inhemoglobinopathies, thalassemia, and liver disease. Acanthocytes have irregular spicules on their surfaces; numerous acanthocytes can be seen in abetalipoprotein-emia. Echinocytes (burr cells) have smooth undulations on their surface; they may be seen in uremia or more commonly as an artifact.
Schistocytes are erythrocyte fragments (helmet cells are a type of schistocyte); theycan be seen in microangiopathic hemolytic anemias or traumatic hemolysis. Bitecells are erythrocytes with “bites” of cytoplasm being removed by splenic macro-phages; they may be seen in G6PD deficiency. Teardrop cells (dacrocytes) may be seen in thalassemia and myelofibrosis. Sickle cells (drepanocytes) are seen in sickle cell anemia. Rouleaux (“stack of coins”) refers to erythrocytes lining up in a row. Rouleaux are characteristic of multiple myeloma.
Basophilic stippling results from cytoplasmic remnants of RNA; it may indicatereticulocytosis or lead poisoning. Howell-Jolly bodies are remnants of nuclear chro-matin that may occur in severe anemias or patients without spleens. Pappenheimerbodies are composed of iron, and they may be found in the peripheral blood follow-ing splenectomy. Ring sideroblasts have iron trapped abnormally in mitochondria, forming a ring around nucleus; they can be seen in sideroblastic anemia. Heinz bod-ies result from denatured hemoglobin; they can be seen with glucose-6-phosphatedehydrogenase deficiency.