Crenated RBCs (Echinocytes)

Crenated RBCs (Echinocytes)

Background Information of Crenated RBCs (Echinocytes)

Echinocytes or the most commonly known crenated RBCs are a shape abnormality seen in blood. Its non-specific clinical significance is often lead to their presence being neglected.  They are characteristically seen with spiny projections dispersed regularly around the cell surface and contains adequate hemoglobin

Clinical Significance

When crenated RBCs are seen in the good-for-examination area of a well-made smear using fresh blood, these cells are actual RBC shape abnormality. These cells are characteristically found in post splenectomy patients with enzayme abnormalities of the erythrocyte glycolysis system.

• Pyruvate Kinase deficiency: The RBC glycolysis system is disrupted leading to lack of ATP which then impairs the NA+/K+ ATPase and ATP-dependent processes, resulting in the cellular loss of K+ and water and increased intracellular NA+ accumulation.
• Drugs (Salicytes, phenylbutazone, fluorsemide) and chemotherapeutic agents (Aoxorubicin): these causes the expansion of the leaflet of the RBC membrane.

Non-Clinical Significiance

Crenated RBCs are often found in smear that have been dried for too long and "aging" of the blood in EDTA tube. Furthermore older RBCs that are nearing their half-life are more prone to this transformation into crenated configuration. More commonly, crenated RBCs are found in underfilled EDTA collection tubes (diagram below) and corrective actions such as making a new smear or re-collecting the sample must be performed.

Hence, when seen on PBFs, these crenated RBCs are actually artefactual and have no clinical value.True burr cells are less numerous.
 


Cellular Description

The hallmark of crenated RBCs/Echinocytes is the presence of RBCs that have numerous evenly spaced projections surrounding the membrane. They are stained normally as they still contain adequate hemoglobin. 

However Echinocytes are often not reported as they are often seen as artefacts in many cases and is a non-specific abnormality, hence it is difficult to distinguish the "real" echinocytes from artifacts.