Heinz body hemolytic animea. "Bite cells" -a clue to diagnosis

Morphologically abnormal red blood cells were noted on routine Wright-stained peripheral blood smears of two patients with Heinz body hemolytic anemia. The abnormal cells had the appearance of having had a piece bitten and are, therefore, termed "bite cells". In the two cases presented, these bite cells led to the suspicion of oxidative hemolysis, which was demonstrated in each case. Both patients were being treated with phenazopyridine hydrochloride when anemia developed. In each case, withdrawal of this drug led to correction of the anemia and the disappearance of bite cells from the blood.