The presence on a Wright-stained peripheral blood smear of relatively evenly-distributed dark-blue particles or granules of varying size in the cytoplasm of erythrocytes is referred to as basophilic stippling. These dark-blue or blue-purple granules are predominantly precipitates of ribosomes (RNA) and may indicate impaired hemoglobin synthesis, probably due to the instability of RNA in the young cell. The erythrocyte containing these inclusions may stain normally in other respects or it may be polychromatophilic.
The basophilic stippling that is clinically significant is referred to as coarse stippling. Fine stippling is often noted in polychromatophilic red cells, and sometimes in other red cells, and is generally not significant. Fine stippling is thought to be artifactual and occurs during the drying of the red cells during slide preparation.
Coarse basophilic stippling may be seen in lead poisoning (or other heavy metal poisoning), thalassemias, and anemias associated with abnormal heme synthesis such as sideroblastic anemia.
