Spherocytes

Spherocytes are abnormally round red blood cells that have a reduced surface area relative to their volume. On the peripheral blood smear they appear as small, spherical cells with little or no central pallor. They are typically more opaque and have an increased mean corpuscular hemoglobin concentration (MCHC). Their reduced deformability makes them prone to destruction by the spleen, causing predominantly extravascular hemolysis.

Most commonly, spherocytes arise from hereditary spherocytosis, an inherited disorder caused by defects in red cell membrane proteins such as spectrin, ankyrin, band 3, or protein 4.2. This weakens the cytoskeletal-membrane interactions and leads to membrane loss over time. Acquired spherocytes occur in autoimmune hemolytic anemia, where autoantibodies bind red cells and the spleen removes membrane blebs. Other causes include severe burns, mechanical trauma, certain drugs, and less commonly other hemolytic conditions.

Clinical presentation ranges from mild to moderate anemia with fatigue, jaundice, and splenomegaly. Chronic hemolysis can lead to pigmented gallstones. Newborns with high bilirubin may have neonatal jaundice. Laboratory findings include reticulocytosis, elevated indirect bilirubin, decreased haptoglobin, and elevated lactate dehydrogenase. Smear shows spherocytes; MCHC is often increased. Diagnostic tests such as the osmotic fragility test and eosin-5′-maleimide (EMA) binding test support hereditary spherocytosis.

Management depends on the cause and severity. Folic acid supplementation supports erythropoiesis; occasional red cell transfusions are used for severe anemia. In hereditary spherocytosis, splenectomy can reduce hemolysis and transfusion requirements but increases infection risk, so vaccination and long-term infection prophylaxis are considered. Addressing complications such as gallstones is also important. Autoimmune cases are treated with immunosuppression, including corticosteroids or rituximab when refractory.