Childhood leukemia is a type of cancer that affects the blood and bone marrow in children. It occurs when the body produces an excessive number of abnormal white blood cells, which can interfere with the production of healthy blood cells. The most common types of childhood leukemia are acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Symptoms of childhood leukemia may include fatigue, frequent infections, easy bruising, and unexplained fevers. Diagnosis typically involves blood tests and a bone marrow biopsy. Treatment options often include chemotherapy, radiation therapy, and sometimes stem cell transplants to help restore healthy blood cell production.