Evaluate the following clinical presentations and pair each patient with the most likely predominant morphologic abnormality expected on their peripheral blood smear.
- A 28-year-old man with a history of recurrent childhood dactylitis who now presents with acute chest pain, hypoxia, and new pulmonary infiltrates.Howell-Jolly bodies
- A 22-year-old man who develops dark urine, fatigue, and scleral icterus three days after initiating oral trimethoprim-sulfamethoxazole for cellulitis.Bite cells (degmacytes)
- A 41-year-old woman admitted with fever, acute confusion, a platelet count of 22,000/mm³, and an elevated serum creatinine level.Schistocytes
- A 33-year-old woman with systemic lupus erythematosus exhibiting new-onset fatigue, elevated indirect bilirubin, and a strongly positive direct Coombs test.Spherocytes lacking central pallor
Answer
The pairings are: the sickle cell disease patient with Howell-Jolly bodies, the G6PD deficiency patient with bite cells, the TTP patient with schistocytes, and the AIHA patient with spherocytes.
Each peripheral smear finding is directly tied to the mechanism of red blood cell injury or clearance. Howell-Jolly bodies reflect loss of splenic macrophage clearance functions (autosplenectomy). Bite cells reflect active splenic macrophage removal of precipitated hemoglobin (Heinz bodies) due to oxidative stress. Schistocytes indicate intravascular mechanical trauma. Spherocytes indicate extravascular partial membrane removal by splenic macrophages responding to bound IgG.
Step-by-Step Solution
Key Concept
Distinct pathophysiologic mechanisms of red blood cell disorders directly correlate with pathognomonic morphological abnormalities on a peripheral blood smear.