How Is Childhood Leukemia Diagnosed?
Most of the signs and symptoms that children with leukemia develop result from a lack of normal blood cells, which happens when the leukemia cells crowd out the normal blood cell-producing bone marrow. It is important to keep in mind that many of these symptoms have other causes as well, and are not necessarily due to leukemia.
A child may complain of excessive tiredness, or the skin may appear pale because of anemia (a shortage of red blood cells).
A child with leukemia may develop an infection with fever that doesn't
improve, even with antibiotics, and become very sick. This is because of a deficiency of normal white blood cells, particularly mature granulocytes. Although leukemia is a cancer of white blood cells and children with leukemia may have very high white blood cell counts, the leukemia cells do not protect against infection the way normal white blood cells do.
A child with leukemia may bruise easily or have increased bleeding from small cuts and nosebleeds. There may be pinhead-sized red spots on the skin that represent bleeding from tiny blood vessels. This results from poor production of blood platelets, which are important for plugging holes in damaged blood vessels.
About one third of the children with leukemia will have bone pain. A smaller number will have joint pain. This is due to accumulation of the leukemia cells underneath the covering of the surface of the bone or inside the joint.
Leukemia often causes enlargement of the liver and spleen. Enlargement of these organs would be noticed as a fullness, or even swelling, of the belly. The lower ribs usually cover these organs but when they are enlarged, the doctor can feel them. Some children will also have a lack of appetite.
Leukemia can spread to lymph nodes. The child, a parent, or a health care professional may notice swollen nodes in certain areas that are close to the surface of the body (on the sides of the neck, in the groin, underarm areas, above the collarbone, etc.). Swelling of lymph nodes inside the chest or abdomen may also occur. These are usually detected only by imaging tests, such as CT or MRI scans.
The T-cell type of acute lymphocytic leukemia (ALL) often involves the thymus gland. Enlargement of the thymus or of lymph nodes inside the chest can compress the nearby trachea (windpipe). This can lead to coughing, upper chest. This is known as SVC syndrome, and can affect the brain and threaten the child's life. Patients with SVC syndrome need immediate treatment.
Leukemia can spread outside the bone marrow. It may involve the central nervous system (brain and spinal cord), the testicles, ovaries, kidneys, lungs, heart, intestines, or other organs. Spread to the central nervous system at the time of initial diagnosis is seen in 5% to 10% of children with leukemia. Headache, poor school performance, weakness, seizures, vomiting, difficulty in maintaining balance, and blurred vision can be symptoms of central nervous system leukemia.
In children with acute myelogenous leukemia (AML),
leukemia cells may spread to the gums, causing swelling, pain, and bleeding. Spread to the skin can cause small darkly colored spots that can resemble common rashes. A collection of AML cells under the skin or other parts of the body is called a or .
One unusual but very serious consequence of AML is extreme tiredness, weakness, and slurring of speech, which occurs when very high numbers of leukemia cells make the blood too "thick" and interfere with circulation through small blood vessels of the brain.
Most of the symptoms of leukemia are not unique. Some of these symptoms can also be caused by other problems like infections. For these reasons, an accurate diagnosis is needed and the best way to do this is for your doctor to examine your child's blood counts. If these are abnormal, your doctor may refer your child to a pediatric cancer specialist.
Blood counts and blood smears are done on samples drawn from a vein or from a "fingerstick." Changes in the numbers of different cell types in the blood and the appearance of these cells under the microscope often make the doctor suspect leukemia.
Most children with acute leukemia (ALL or AML) will have too many white cells in their blood and not enough red blood cells andlor not enough platelets. In addition, many of the white blood cells in the blood will be , a type of cell normally found in the bone marrow but not in circulating blood. Even though these findings may make a doctor suspect that leukemia is present, usually the disease cannot be diagnosed for sure without obtaining a sample of bone marrow cells.
Bone marrow aspiration involves removing a small amount of bone marrow. Usually the sample is taken from the pelvic (hip) bone. First the bone is numbed with a local anesthetic. In some cases, the child is also given other medications to reduce pain or even put him or her to sleep during the procedure. A thin needle attached to a syringe is then put through the outer bone into the marrow space, where some marrow is sucked out (aspirated).
A biopsy often follows, during which a small cylindrical piece of bone and bone marrow (about 1116-inch in diameter and 112-inch long) is removed. Both samples generally are taken at the same time. These tests are used for the initial diagnosis and are repeated later to tell if the leukemia is responding to therapy.
