Background Information of Spherocytes
Spherocytes are RBCs that have a molecular defect in 1 or more proteins in the RBC cytoskeleton. The cytoskeleton of RBCs are typically composed of Spectrin, Ankyrin, Band 3 or Protein 4.2. Due to their cytoskeleton defect, the RBC contracts to its most surface-tension efficient and least flexible configuration, which is the sphere-like shape (as the name implies). However this configuration is susceptible to high osmotic fragility and prone to physical degeneration.
Appearance of numerous spherocytes without other abnormal RBCs on a PBF is highly indicative of Hereditary spherocytosis. If small numbers of spherocytes is seen in conjunction with other abnormal RBCs are seen in PBFs, the following clinical conditions may be suspected:
- Isoimmune and autoimmune hemolytic anemias
- Heinz body hemolytic anemia
- Hereditary pyropoikilocytosis
- Microangiopathic hemolytic anemia
- Myelofibrosis with myeloid metaplasia
- Liver disease
- recent transfusions
- severe burns.
The hall mark of spherocytes is the presence of numerous small RBCs that appear synonymous to a sphere-like shape without a visible central pallor and is stained more densely than their normal counterparts. The denser staining is due to the normal concentration of hemoglobin being "concentrated" due to the shrinkage of the RBCs.