What is the MOST likely cause of bruising in a patient with advanced-stage leukemia and anemia?

In a patient with advanced-stage leukemia and anemia, thrombocytopenia is the most likely cause of bruising. Leukemia often leads to bone marrow infiltration by malignant cells, which can disrupt normal blood cell production, including that of platelets. A decrease in platelet count results in thrombocytopenia, a condition characterized by an abnormally low level of platelets in the blood. Since platelets play a crucial role in blood clotting and hemostasis, a reduced platelet count significantly increases the risk of bleeding and bruising even from minor trauma or spontaneously.

This mechanism explains the bruising observed in these patients, where the underlying hematological disorder has a direct impact on the clotting cascade. While other conditions such as hemophilia, vitamin deficiencies, or liver dysfunction can also lead to bleeding tendencies, the scenario described is most closely aligned with the typical complications arising from thrombocytopenia associated with leukemia.