A 7-year-old Vietnamese boy is brought to the clinic for a routine health maintenance examination. He underwent a splenectomy a year ago for persistent anemia and jaundice. He has received the pneumococcal and meningococcal vaccinations and takes penicillin prophylaxis. His paternal uncle died from complications of hemolytic uremic syndrome 35 years ago. Physical examination reveals a well-appearing child. The sclerae are anicteric. The abdomen is soft and nontender; no masses are palpable. Several well-healed laparoscopy scars are noted. Complete blood count is as follows:
| Hemoglobin | 11.3 g/dL |
| Reticulocytes | 3% |
| Platelets | 160,000/mm3 |
| Leukocytes | 8,200/mm3 |
Peripheral blood smear with Wright stain is shown in the exhibit. This patient's findings are most likely related to which of the following?
Show Explanatory Sources
This patient has single, round, blue inclusions within red blood cells (RBCs) on peripheral smear, consistent with Howell-Jolly bodies. These bodies are retained RBC nuclear remnants that are typically removed by the spleen. The presence of Howell-Jolly bodies usually indicates either physical absence of the spleen (ie, asplenia) due to congenital absence or surgical removal or functional hyposplenism due to splenic autoinfarction (eg, sickle cell disease), infiltrative disorders of the spleen (eg, sarcoidosis), or splenic congestion (eg, thrombosis).
Both asplenia and functional hyposplenism increase the risk of sepsis because the spleen is normally responsible for clearing bacteria, particularly encapsulated organisms. However, splenectomy may be indicated in cases of chronic hemolysis.
(Choice A) In glucose-6-phosphate dehydrogenase deficiency disease, hemoglobin becomes oxidized and precipitates into insoluble Heinz bodies. Peripheral smear shows bite cells, and Heinz bodies appear as peripheral blue inclusions with special staining (eg, crystal violet), not with Wright staining as in this patient.
(Choice B) The inability to produce alpha (alpha thalassemia) or beta (beta thalassemia) globin chains causes hypochromic, microcytic RBCs and target cells (due to decreased hemoglobin production), which can be seen on peripheral smear.
(Choice C) Mechanical RBC damage occurs when RBCs shear within the vascular system. This occurs in hemolytic uremic syndrome, disseminated intravascular coagulation, and thrombotic thrombocytopenic purpura. Schistocytes (fragmented RBCs) are seen on peripheral blood smear.
(Choice E) Precipitation of ribosomal ribonucleic acid is seen in patients with lead poisoning. In contrast to the single, blue, peripherally-located inclusion characteristic of a Howell-Jolly body, basophilic stippling appears as multiple, scattered, blue granules within the RBC cytoplasm.
Educational objective:
Howell-Jolly bodies are nuclear remnants within red blood cells typically removed by the spleen. Their presence strongly suggests asplenia or functional hyposplenism.