Erythrocyte inclusions may be present in red blood cells (RBCs). Each type of inclusion has a specific appearance, composition, and associated physiology. Identifying and reporting these inclusions is essential because their presence may indicate diseases or disorders.
One of the functions of the spleen is pitting, which refers to its ability to pluck out particles in red blood cells without destroying them. The presence of red blood cell inclusions in a peripheral blood smear can indicate an increased number of inclusionary bodies, so much so that the spleen can not keep up by removing them all. This is where red cell inclusions may indicate a disease state. Additionally, increased red blood cell inclusions may be observed on a peripheral blood smear if a person has had a splenectomy.
Many erythrocyte inclusions can be visualized on a Wright-stained smear. However, some erythrocyte inclusions can only be observed using a particular stain. For example, to confirm the presence of Heinz bodies, hemoglobin H bodies, or reticulocytes, smears must be prepared after staining an aliquot of fresh whole blood with a supravital stain such as new methylene blue or brilliant cresyl blue. The image on the right is a peripheral blood smear prepared after staining the blood sample with a supravital stain; the arrows indicate Heinz bodies, which are clumps of precipitated hemoglobin.
To detect siderosomes, a stain specific for iron, such as Prussian blue, must be used.
