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What are petechiae and ecchymoses in thrombocytopenia?

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blood disease Peripheral blood smear revealing histopathologic features indicative of a blast crisis in a case of chronic myelogenous leukemia (CML). Blast crisis occurs when one-fifth to one-third of the cells in the blood or bone marrow are immature blood cells, or blast cells. This phase of CML is characterized by fever, weakness, and an enlarged spleen.

In the context of thrombocytopenia, which is characterized by an abnormally low number of platelets in the circulation, petechiae and ecchymoses are clinical manifestations of spontaneous hemorrhage into the skin.1

Petechiae: These appear as tiny, purplish spots on the skin caused by small hemorrhages. They result from the escape of blood into the tissues due to the scarcity of platelets, which are essential for maintaining vascular integrity and clotting.12
Ecchymoses: These are larger, black-and-blue areas of discoloration in the skin. Like petechiae, they are caused by bleeding into the skin, but they represent more extensive hemorrhaging.13

These signs occur because, without a sufficient number of platelets, the body struggles to repair the small, routine injuries that occur in capillaries, leading to these visible indicators of bleeding disorders.13