A 21-year-old man develops dark urine, jaundice, and back pain two days after receiving primaquine for malaria prophylaxis. His maternal uncle has a similar history after eating fava beans. Peripheral smear shows red cells with a peripheral cluster of hemoglobin that appears to have been scooped out. The most likely diagnosis is:
- A Hereditary spherocytosis
- B Paroxysmal cold hemoglobinuria
- C G6PD deficiency with oxidative hemolysis ✓
- D Microangiopathic hemolytic anemia
Correct answer: C. G6PD deficiency with oxidative hemolysis
Explanation
G6PD deficiency is X-linked and causes episodic intravascular hemolysis after oxidant stress such as primaquine, sulfonamides, nitrofurantoin, or fava beans. Bite cells form when splenic macrophages pluck out Heinz bodies (precipitates of oxidized, denatured hemoglobin), leaving the characteristic scooped appearance. Hereditary spherocytosis is lifelong spherocytosis without oxidant triggers, paroxysmal cold hemoglobinuria is mediated by the Donath-Landsteiner antibody, and MAHA shows schistocytes rather than bite cells.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.