Diagnosis

Doctors use many tests to diagnose cancer and determine if it has spread. Some tests may also determine which treatments may be the most effective. A patient history, physical examination, complete blood cell count (CBC), and bone marrow aspiration (see below) are the main procedures used to diagnose ALL, and each is used to establish a diagnosis of ALL or rule out other conditions (called differential diagnosis).

Blood tests. A CBC provides a count of each type of cell in the blood. The blood count may also show abnormal leukemic cells. The blood count is abnormal, in some way, in nearly all children with ALL at the time of diagnosis.

Bone marrow aspiration. A bone marrow aspiration is recommended if the blood test shows unusual blood counts or immature cells in the blood, or if the doctor suspects that a child may have leukemia. For this test, a sample of bone marrow is removed from the child’s hip with a needle and examined under a microscope. From this test, the doctor can determine whether the child has leukemia and, if so, what type of leukemia it is. The doctor or nurse will collect multiple samples of bone marrow at the same time for other tests, such as chromosome and molecular genetic analyses and immunophenotyping (see Classification). These additional tests may be important to determine which treatment is most appropriate.

Lumbar puncture (spinal tap). A lumbar puncture can determine if the leukemia has spread to the spinal fluid. A lumbar puncture is a procedure in which a doctor takes a sample of cerebral fluid (CSF) to look for cancer cells, blood, or tumor markers (substances found in higher than normal amounts in the blood, urine, or body tissues of people with certain kinds of cancer). CSF is the fluid that flows around the brain and the spinal cord. Doctors generally give an anesthetic to numb the lower back before the procedure. The presence or absence of leukemia in the central nervous system will determine, in part, the most appropriate treatment. There may be times when it is appropriate to deliver medicine to treat or prevent leukemia of the central nervous system at the same time that the lumbar puncture is done. 

To learn more about what to expect during common diagnostic tests, read Cancer.Net: Tests and Procedures.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: Newly Diagnosed.