Childhood Leukemias: Acute vs. Chronic vs. Congenital

Little Girl with Leukemia
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When the topic of leukemia is raised, many people have a vague awareness that this can be a children’s disease. But after that, the details seem to get somewhat blurred. It should be noted that, while leukemia is the most common childhood malignancy, it is also true that childhood leukemia is still pretty rare.

Chronic vs. Acute Leukemia

Acute leukemias tend to develop rapidly. The malignant cells—called blasts—are immature and have not developed enough to carry out their immune system functions. In contrast, chronic leukemias develop in more differentiated or mature cells, which can perform some of their duties, but not very well. The abnormal cells of chronic leukemias usually multiply at a slower rate than acute leukemias. However, chronic leukemias are very rare in children.

Most childhood leukemias are acute lymphocytic leukemia (ALL). Most of the remaining cases are acute myeloid leukemia (AML). The 'myeloid' and 'lymphocytic' terms in these names refer to two different families of cells: those that will give rise to lymphocyte white blood cells (lymphocytic); and those that will give rise to red blood cells, platelets, and the rest of the white blood cells such as monocytes, neutrophils, and more.

Childhood vs. Congenital Leukemia

While leukemia is the most common malignancy in childhood, congenital leukemia is quite rare, comprising less than 1 percent of all childhood leukemias. The condition is defined as a leukemia that occurs within 4 to 6 weeks of birth. It's thought that this malignancy begins to develop before the baby is even born.

Unfortunately, the 6-month survival rate is only one-third, despite aggressive chemotherapy. However spontaneous remissions have been reported, but science has not offered definitive answers as to how this might occur.

The fact that these rare miracles have been reported, can complicate the therapeutic decision-making process for doctors and parents. Some have wondered whether a more conservative approach to treatment, especially early on, is warranted.

It should be noted that congenital leukemias are not the only leukemias to be reported to seemingly resolve. Spontaneous remissions occur in other types of leukemia as well, and the remission may be transient, or short-lived, or more durable, depending on the reported case.

Childhood Leukemia Statistics

Though leukemia is the most common cancer in children and teens, overall, childhood leukemia is still a rare disease. About 75 percent of leukemias among children and teens are ALL, and most of the remaining cases are AML.

According to the statistical review by the American Cancer Society, ALL is most common in early childhood, peaking between 2 and 4 years of age. Cases of AML are more spread out across the childhood years, except that AML is slightly more common during the first 2 years of life and during the teenage years.

In terms of race and ethnicity, ALL is slightly more common among Hispanic and white children than among African-American and Asian-American children, and it is more common in boys than in girls. AML occurs about equally among boys and girls of all races.

Chronic leukemias are rare in children, but when they do occur, most of these tend to be chronic myelogenous leukemia (CML), which tends to affect more youngsters in the teenage group than in younger children. Juvenile myelomonocytic leukemia (JMML) usually occurs in young children, with an average age of about 2 years.

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