Acanthocytosis
Description: Irregularly spiculated RBC with projections of varying length and position
Associated Disease: Abetalipoproteinemia alcoholic liver disease Postsplenectomy, Malabsorptine states

Anisocytosis
Description: Abnormal variation in size
Associated Diseases: Any severe anemia

Basophilic stippling
Description: Punctate stippling when Wright-stained
Associated Diseases: Hemolytic anemia, lead poisoning, Thalassemia

"Burr" cells
Description: Spiculated RBC with short, equally spaced projections over entire surface
Associated Diseases: Hemolytic anemias, liver disease, normal infants, uremia, microangiopathic hemolytic anemia, disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, pyruvate kinase deficiency, carcinoma

Cabot rings
Description: Purple, fine, ring-like, intraerythrocytic structures
Associated Diseases: Pernicious anemia, lead poisoning

Elliptocytes
Description: Oval cells
Associated Diseases: Hereditary elliptocytosis, iron deficiency

Heinz inclusion bodies
Description: Small round inclusions seen under phase microscopy or with supravital staining
Associated Diseases: Congenital hemolytic anemias (eg, glucose 6-phosphate dehydrogenase deficiency), hemolytic anemia secondary to drugs (dapsone, phenacetin), thalassemia (Hb H), hemoglobinopathies (Hb Zurich, Kln, Ube, 1, etc)

Howell-Jolly bodies
Description: Spherical purple bodies (Wright's stain) within or on erythrocytes; nuclear debris
Associated Diseases: Hyposplenism, pernicious anemia

Hypochromia
Description: Pale cells with decreased concentration of hemoglobin (MCHC > 31 g/dL)
Associated Diseases: Iron deficiency and iron-loading (sideroblastic) anemia, thalassemia, lead poisoning, transferrin deficiency, anemia of chronic disease (inflammatory diseases, eg, rheumatoid arthritis, collagen diseases, malignancies)

Macrocytosis
Description: Large cells, greater than 8 um MCV > 100 fl
Associated Diseases: Megaloblastic anemia, liver disease, hypothroidism, hemolytic anemia (reticulocytes), multiple myelome, physiologic macrocytosis of newborn, myelophthisis

Macro-ovalocytosis
Description: Large > 8 m oval cells MCV > 100 fl
Associated Diseases: Megaloblastic anemia

Mircocytosis
Description: Small cells, less than 6 um MCV < 80 fl
Associated Diseases: Iron deficiency and iron-loading (sideroblastic) anemia, thalassemia, lead poisoning

Nucleated red cells
Description: Erythrocytes with nuclei still present; may be normoblastic or megaloblastic
Associated Diseases: Hemolytic aneamias, leukemias, myeloproliferative syndrome, polycythemia vera, myelophthisic anemia (neoplastic, granulomatous, or fibrotic marrow infiltration), multiple myeloma, extramedullary hematopoiesis, megaloblastic anemias, any severe anemia

Pappenheimer bodies (siderocytes)
Description: Siderotic granules, staining blue with Wright's or Prussian blue stains
Associated Diseases: Iron-loading anemias, hyposplenism, hemolytic anemias

Poikilocytosis
Description: Abnormal variation in shape
Associated Diseases: Any severe anemia - eg, megaloblastic, iron deficiency, myeloproliferative syndrome, hemolytic; certain shapes are diagnostically helpful

Polychromasia
Description: RBCs containing RNA, staining a pinkish blue color; stains supravitally as reticular network with new methylene blue
Associated Diseases: Hemolytic anemia, blood loss, uremia, following treatment of iron deficiency or megaloblastic anemias

Rouleaux
Description: Aggregated erythrocytes regularly stacked on one another
Associated Diseases: Multiple myeloma, Waldenstrm's macroglobulinemia, cord blood, pregnancy, hypergammaglobulinemia, hyperfibrinogenemia

Schistocytes
Description: Red cell fragments of any size or shape including helmet, horny, blister, or other irregular unusual or unclassifiable shapes
Associated Diseases: Uremia, carcinoma, hemolytic-uremic syndrome, disseminated intravascular coagulation, microangiopathic hemolytic anemia, toxins (lead, phenylhydrazine), burns, thrombotic thrombocytopenic purpura

Sickle cells
Description: Crescent-shaped cells
Associated Diseases: Sickle cell hemoglobinopathies

Spherocytosis
Description: Spherical cells without pale centers; ofter small, ie, microspherocytosis
Associated Diseases: Hereditary spherocytosis, Coombs' - positive hemolytic anemia; small numbers are seen in any hemolytic anemia and after transfusion of stored blood

Stomatocytosis
Description: Red cells with slit-like, instead of circular, area of central pallor
Associated Diseases: Congenital hemolytic anemia, thalassemia, burns, lupus erythematosus, lead poisoning, liver disease, artifact

Target cells
Description: Cells with a dark center and periphery and a clear ring in between
Associated Diseases: Liver disease, thalassemia, hemoglobinopatheis (S, C, SC, S-thalassemia)

Teardrop cells
Description: Cells shaped like teardrops
Associated Diseases: Myeloproliferative syndrome, myelophthisic anemia (neoplastic, granulomatous, or fibrotic marrow infiltration), anemia with extramedullary hematopoiesis or ineffective erythropoiesis

¤Reich, Paul R, M.D., Hematology: Physiopathologic Basis for Clinical Practice
Boston, MA: Little, Brown & Company (Inc), 1984, 19-21.