Howell-Jolly bodies are small, round inclusions found within red blood cells. They are composed of DNA and are a result of nuclear fragmentation during the maturation of the red cell. Howell-Jolly bodies arise due to incomplete nuclear expulsion, or from a chromosome that has separated from the mitotic spindle during abnormal mitosis. They may be found in the bone marrow of normal individuals but are removed by the spleen and so are not seen in the peripheral blood. Their presence in peripheral blood and hence on a blood film is due to decreased splenic function or if the patient has had their spleen removed (splenectomy). Howell Jolly bodies can be a normal finding in the blood of neonates as their spleen isn’t functionally mature.
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