Petechiae are pinpoint-shaped spots of blood that form under the skin. Although leukemia isn't the only possible cause of petechiae, the skin symptom is very common among people who have this form of blood cancer. Research suggests that leukemids - nonleukemic skin signs of leukemia, including leukemia petechiae - may occur in more than 40 percent of people who have leukemia.

Petechiae are tiny, round spots on the skin that appear to be red, purple, or brown. These spots are usually flat and often develop in clusters. At a distance, these qualities can make petechiae appear as a skin rash, although the marks usually do not cause itching or inflammation

Petechiae are nonblanching, which means that they don't lighten in color when you apply pressure to them. Notably, all petechiae are smaller than 2 millimeters in size - those that grow bigger are known as purpura. Usually, marks of either size form and fade within a few days.