An 8-year-old boy is brought to the office for evaluation of bilateral leg and back pain. His pain started yesterday and has gradually worsened. He has had no relief with ibuprofen, acetaminophen, and warm packs. The patient's medical history is notable for sickle cell disease, and he has had 5 prior hospitalizations for similar pain episodes in his back and legs. Hydroxyurea has been prescribed, but the prescription has not been filled due to lack of insurance. Temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, pulse is 132/min, and respirations are 20/min. Physical examination shows an uncomfortable-appearing boy with conjunctival pallor. Palpation of the bilateral legs and back shows tenderness, although no erythema or swelling is noted. Laboratory results are as follows:
| Complete blood count | |
| Hemoglobin | 8.2 g/dL |
| Hematocrit | 26% |
| Mean corpuscular volume | 84 fL |
| Reticulocytes | 8% |
| Platelets | 380,000/mm3 |
| Leukocytes | 17,000/mm3 |
What finding is most likely to be present on this patient's peripheral smear?
Show Explanatory Sources
This patient with sickle cell disease (SCD) has a typical vaso-occlusive pain crisis and a history of similar episodes. Repeated microinfarctions from the clumping of sickle cells can destroy splenic tissue, leading to microvascular beds that promote sickling. This chronic damage and autoinfarction of the spleen leads to functional asplenia by age 5 in patients with SCD.
Because the spleen normally plays an important immunologic role in clearing bacteria from the blood, functional asplenia leads to susceptibility to infection, particularly from encapsulated bacteria (eg, Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis). A functional spleen also removes normal nuclear remnants of red blood cells, or Howell-Jolly bodies. In patients with a history of splenectomy or functional asplenia, as in this patient, Howell-Jolly bodies would be an expected finding on peripheral smear. They appear as small purple dots within the red blood cell.
(Choice A) Basophilic stippling (black arrows) represents ribosomal precipitates that appear as blue granules of various sizes dispersed throughout the cytoplasm of red blood cells. It is seen with thalassemias as well as lead or heavy metal poisoning.
(Choices B and C) Heinz bodies, which appear as small inclusions within an erythrocyte, are aggregates of denatured hemoglobin and are commonly seen in patients with hemolysis due to glucose-6-phosphate dehydrogenase deficiency and thalassemia. When phagocytes extract this rigid precipitate, they form characteristic bite cells (black arrow).
(Choice D) Helmet cells, or schistocytes (black arrows), are fragmented red blood cells. Their presence suggests traumatic microangiopathic hemolytic conditions such as disseminated intravascular coagulation, hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura. Helmet cells are not typically seen in SCD as this hemolysis is intrinsic, not traumatic.
Educational objective:
Howell-Jolly bodies are nuclear remnants of red blood cells that are usually removed by a functional spleen. Due to functional asplenia in sickle cell patients, Howell-Jolly bodies are expected findings on peripheral smear.