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Under normal conditions, Howell-Jolly bodies are thought to be remnants of nuclear fragments due to incomplete expulsion of the nucleus. In pathological conditions, they are aggregates of chromosomes which have separated from the mitotic spindle during abnormal mitosis. Single or multiple Howell-Jolly bodies may be found in a red cell. A single HJ body in a red cell may be seen in megaloblastic anemia, hemolytic anemia such as sickle cell anemia and after splenectomy. Megaloblastic anemia or abnormal erythropoiesis is usually present when multiple Howell-Jolly bodies are observed in a single cell.

A nucleated red cell containing siderotic granules clustered around the nucleus is shown by the arrow. This is called a ring sideroblast and is seen only in pathological conditions. A siderocyte is also present toward the lower left.

20 to 60% of red cell precursors seen in bone marrow slides normally contain siderotic iron granules visible with Prussian Blue stain. The presence of sideroblasts and siderocytes indicates that the red cell precursors have an ample supply of iron. When a red cell precursor contains too much iron, the siderotic granules form a ring around the nucleus and the resulting cells are referred to as ring sideroblasts. The ring sideroblast is an abnormal (pathological) form of sideroblast.

Pappenheimer bodies are iron-containing granules that aggregate with mitochondria and are deposited in RBC or normoblast cytoplasm. Small and irregular, they are found only in pathological states as thalassemia and sideroblastic anemias(upper image). Wright-Giemsa stain defines the cytoplasmic content (protein), but Prussian blue staining is necessary to define the iron content, the essence of the Pappenheimer body (lower image). Pappenheimer bodies lie typically in small clusters (upper image) and tend to locate at the periphery of the red cell cytoplasm. A cluster is typically smaller than a single Howell-Jolly body.

It is important to be able to recognize the presence of these changes and then identify them for several reasons:If the changes are pathological, their identification may aid the physician in diagnosing a specific condition.If the changes are not pathological, their identification alerts the physician to the fact that the changes are present, thus avoiding a possible misdiagnosis.If reactive, it indicates that although the cells are functioning normally, they are reacting to a stimulus. Indicating the presence of such cells may aid in determining the diagnosis or monitoring the course of disease once a diagnosis has been made.

A normal mature neutrophil is 9-13 microns in diameter and contains 3-5 lobes or segments.When the number of segments is increased to six or more the cell is hypersegmented. Some hypersegmented cells will be larger than in 15 microns. Hypersegmentation is seen most frequently in neutrophils but can also occur in eosinophils and basophils. The nuclear segments are composed of deoxyribonucleic acid (DNA). A defect in the production of DNA causes the maturation process to be slower than normal which in turn causes the nucleus to hypersegment. The cytoplasm will be normal in appearance and function, indicating that these cells are capable of phagocytosis.These cells are considered pathological

There are a number of conditions in which hypersegmented neutrophils may be seen, such as megaloblastic anemias that include folic acid deficiency and pernicious anemia. Individuals who are receiving chemotherapy or have long-term chronic infections may also have hypersegmented neutrophils.The cells seen in these conditions would be classified as pathological since the body is responding abnormally as a result of either a deficiency of a component needed for DNA production or because of the toxic effect that chemotherapy drugs have on DNA.

Auer rods are red staining, needle-like bodies seen in the cytoplasm of myeloblasts, and/or progranulocytes in leukemia. Auer rods are cytoplasmic inclusions which result from an abnormal fusion of the primary (azurophilic) granules. Single or multiple Auer rods may be seen in the cytoplasm of a cell. If more than one is present, they are frequently close together and may even be overlapping. Their identification is very important because, if found, they can confirm the presence of myeloblasts indicating the presence of a myeloid (non-lymphoblastic) leukemia. They can also be seen in myeloid blast crisis in chronic granulocytic leukemia. Auer rods are never seen in lymphoblasts. This differentiation is important because the treatment of lymphoblastic and myeloblastic leukemia are different. Auer Rods always classified as pathological.

May-Hegglin anomaly is an autosomal dominant condition characterized by the presence of pale blue inclusions in neutrophils, giant platelets, and sometimes thrombocytopenia. Inclusions can also occur in eosinophils, basophils, and monocytes. May-Hegglin inclusions resemble Dohle bodies but are larger and more prominent. Acquired forms of this anomaly may also occur as a result of the use of cytotoxic drugs. May-Hegglin bodies seen under these circumstances are considered pathological.