Sickle Cells

By William Aird

Peripheral smear from a 27-year-old woman with sickle cell disease. If examined closely at low power, this field shows smear shows many sickle cells (magnified in inset) . With practice, you will pick up this diagnosis at 10x (10x)!

Sickle cell (blue arrow) in a 27-year-old woman with sickle cell disease. Note that it is elongated with pointed ends. These cells are believed to have undergone irreversible shape change (100x, oil).
Nucleated red cell (middle of field), multiple boat cells (blue arrow shows one) and target cells (examples shown with black arrow) in a 36-year-old man with sickle cell disease (50x).

Howell-Jolly bodies resulting from autosplenectomy (blue arrows), multiple boat cells (some shown with black arrows) and polychromatophilic cell (P) in a 19-year-old man with sickle cell disease (100x, oil).
Nucleated red cell (blue arrow) and multiple boat cells (some of these are shown with black arrows) in a patient with sickle cell disease (100x, oil).
Boat cells (blue arrows) and sickle cells (black arrows) in 45- year-old woman with sickle cell disease (50x).

Red blood cell, shape abnormality Sickle cell and boat-shaped cell
Also known asDrepanocyte
Definition Sickle cells are elongated, sometimes crescent-shaped red cells with pointed ends. Boat-shaped cells have the appearance of a canoe viewed from above with sharpened ends. They lack central pallor, and stain deeply. Typically 10-15 um in length with width narrower than normal cells.
Conditions associated with the shape abnormality Sickle cell disease, for example HbSS, HbSC
Mechanism of formationShape change caused by the polymerization/gelation of deoxygenated hemoglobin S
Other findingsDeoxy HbS may also result in crescent-shaped, filament-shaped, holly-leaf form, or envelope cells. These cells usually lack central pallor; polychromatophilic RBCs, target cells, Howell-Jolly bodies.
HistorySCD was first described by James Herrick in 1910. Herrick noted the “sickle”-shaped red cells on the peripheral smear.
Source/authorWilliam Aird
Reviewed and edited byParul Bhargava
ReferencesHerrick JB. Peculiar elongated and sickle-shaped red blood corpuscles in a case of severe anemia. Arch Int Med 1910;6:517