Howell-Jolly bodies are little fragments of the red cell nucleus. You see them most commonly in patients with splenectomies (normally, the spleen just bites them out). You can see them without a special stain – they look like dark, round dots.
Heinz bodies are seen in G6PD deficiency. They represent denatured globin chains. When there’s not enough G6PD around, the bonds between heme and globin are attacked.
What’s the difference between Howell-Jolly bodies and Heinz bodies?
Source: Pathology student