Common findings:

• Target cells (codocytes): liver disease, hemoglobinopathies (i.e. S, E, C), thalassemia, post-splenectomy, iron deficiency.
• Spherocytes: hereditary spherocytosis, autoimmune hemolytic anemia.
• Schistocytes: microangiopathic hemolytic anemias (e.g. DIC, TTP, HUS, mechanical heart valve).
• Burr cells (echinocytes): uremia, liver disease, artifact from smear preparation.
• Spur cells (acanthocytes): severe liver disease, abetalipoproteinemia, malabsorption.
• Teardrop cells (dacrocytes): myelophthistic processes (especially myelofibrosis), myelodysplasia, megaloblastic anemias, thalassemia major.
• Sickle cells (drepanocytes): seen in sickle cell disease.
• Elliptocytes (ovalycytes): hereditary elliptocytosis, thalassemia, iron deficiency, myelophthisic anemias, megaloblastic anemias.
• Howell-Jolly bodies: post-splenectomy/hyposplenism.
• Heinz bodies: requires Heinz body prep. G6PD deficiency, alpha-thalassemia, unstable hemoglobins.
• Basophilic stippling: lead poisoning, thalassemia, hemoglobinopathies, sideroblastic anemias.
• Hypochromia: iron deficiency.
• Anisocytosis: variability in size, seen in a variety of contexts including most anemias.
• Poikilocytosis: term for a number of abnormalities in shape. Also seen in a variety of contexts, including most anemias.
• Polychromasia: variability in RBC color, typically a sign of active erythropoiesis and reticulocytosis.
• Rouleaux: red cell stacking, often looks like a stack of coins. May be an artifact, but also seen with circulating paraproteins.

Bain, B. Diagnosis from the Blood Smear, New Eng J Med 2005 353:498-507.

Bull BS, Herrmann PC. Chapter 29. Morphology of the Erythron. In: Lichtman MA, Kipps TJ, Seligsohn U, Kaushansky K, Prchal JT. eds. Williams Hematology, 8e. New York, NY: McGraw-Hill; 2010.