Pathology refers to the careful examination of tissue under a microscope in order to find out whether it's cancerous or non-cancerous and to determine the type of tumour it is.
Leukemia is a cancer of the blood-forming tissue (bone marrow). It develops in either immature or mature white blood cells from the lymphoid cell line or myeloid cell line.
In general, leukemias are classified as acute (develop rapidly) or chronic (develop slowly). In children, over 90% of leukemias are acute. Chronic childhood leukemias are uncommon and will not be discussed here. Chronic myelogenous leukemia (CML) is rare in children. When it is diagnosed, CML in children is treated much the same as in adults. Chronic lymphocytic leukemia (CLL) is extremely rare in children.
Acute childhood leukemias are divided into 2 types based on which blood cells are affected:
- When lymphoid cells become cancerous, it is called acute lymphoblastic leukemia (ALL).
- When myeloid cells become cancerous, it is called acute myelogenous leukemia (AML).
ALL is the most common type of childhood leukemia, representing 75–80% of cases. About 15–20% of childhood leukemias are AML.
Once the type of leukemia has been diagnosed, the doctor will also consider:
- if the central nervous system (CNS) is involved
- prognostic factors (special characteristics that might influence the course of the disease)
- survival statistics for the particular type and stage of cancer
All of this information helps the doctor make a treatment plan.
See a list of questions to ask your doctor about pathology and staging.