In which two diseases would Howell Jolly bodies be observed on a peripheral smear?

Howell-Jolly bodies are remnants of DNA that are typically found in red blood cells, indicating that the spleen is not effectively filtering or removing these cells. This is often seen in conditions where splenic function is impaired or absent.

In the case of sickle cell anemia, there is a high likelihood of vascular occlusion and splenic dysfunction, leading to the diminished ability of the spleen to remove these nuclear remnants, resulting in Howell-Jolly body formation.

Folate deficiency can also lead to the presence of Howell-Jolly bodies. It is primarily associated with megaloblastic anemia, which can result in ineffective erythropoiesis and alterations in red blood cell maturation. This can indirectly affect the spleen's function, as megaloblastic changes can lead to larger and more abnormal red blood cells, which may not be processed efficiently.

The presence of Howell-Jolly bodies in these two conditions reflects an inadequate spleen function or structural abnormalities associated with these underlying diseases, thereby making the selection of folate deficiency and sickle cell anemia as the conditions that exhibit Howell-Jolly bodies in a peripheral smear correct.