Leukemia is a type of malignant blood cancer and should be treated by a hematologist. Common clinical manifestations of leukemia include infections, anemia, and bleeding. Infections occur because leukemia patients have weak immune systems, potentially leading to severe infections. These infections may affect the lungs, urinary system, or intestines. Anemia can cause leukemia patients to appear pale, feel weak, have poor appetite, and have decreased tolerance for activity. Bleeding may manifest as bleeding gums, nasal bleeding, or bleeding from skin and mucous membranes. When such symptoms appear, a routine blood test should be conducted. If the test indicates a possibility of leukemia, further correction by a hematologist is necessary.