Condensed Case

Summary Points

• Leukemia is caused by the mutation of the bone marrow pluripotent stem cells.

• Individuals with acute leukemia will present with variable white counts, anemia, and platelet counts.

• When blasts cells accumulate in the bone marrow and peripheral smear, the leukemia is classified as acute.

• Hepatosplenomegaly or lymphadenopathy is more prominent in chronic leukemias than in acute leukemias.

• According to the WHO, the peripheral smear must contain 20% myeloblasts or greater for a diagnosis of acute leukemia.

immunophenotypic and cytogenetic profiles, and response to treatment. The two most important tests with the greatest prognostic prediction power when the sample of hematopoietic material is limited are flow cytometry and cytogenetics.

The combination of conventional clinical, morphological, and cytochemistry findings with the newer immunophenotypic, cytogenetic, and molecular testing now available affords the pathologist and oncologist the most valuable and comprehensive information to "get to know" each disease entity and its characteristics. It is now even more imperative that there is good communication between the clinician, the laboratory staff, and the pathologist in gathering the important prognostic data so that the most specific diagnosis and treatment can be applied.

• Skin infiltration is characteristic of monocytic leukemias; extramedullary hematopoiesis is common in monocytic or myelomonocytic leukemias.

• Headache, blindness, and other neurological complications are indicative of blast cells crossing the blood-brain barrier.

• Cytochemical staining can assist in the diagnosis of acute leukemias based on staining patterns.

• Auer rods are composed of fused primary granules and may be present in myeloblasts.

• Immunophenotyping can help to classify the clone of leukemic cells by using monoclonal antibodies in flow cytometry or immunohistochemistry procedures.

A 10-year-old girl was taken to an outpatient clinic with a complaint of sore throat and a lump in her neck. Upon examination she was observed to have a tonsillar abscess, swollen glands, and widespread bruising in the extremities. She also had a low-grade fever. She was treated with antibiotics and released, but she failed to progress in the next 2 days. Her blood work revealed a white count of 8.0 X 109/L, an hematocrit of 28%, and a platelet count of 10,000. Her parents were contacted and she was immediately admitted to the hospital. A bone marrow examination was performed and revealed an infiltration of blast cells in the marrow. Why are her other cell counts depressed?


Although this is an unusual presentation of an acute leukemia, all of the elements related to symptoms are in place. The depressed hematocrit and platelet count are indicative of the blast burden in the bone marrow crowding out all of the normal elements and causing low counts. This young girl will be transferred to an oncology facility and will most likely be treated aggressively for her leukemia after it is classified. What is the presumptive diagnosis based upon this information?

1 Monocyte 83 Blasts

• Cytogenetic abnormalities such as translocation and deletion are an important prognostic feature of many acute leukemias.

• Acute promyelocytic leukemia is associated with disseminated intravascular coagulation.

• Treatment with cytotoxic chemotherapy and/or radiation therapy is associated with the develop ment of acute leukemia and myelodysplastic syndrome.

• Acute myelocytic leukemia with maturation of the most common acute myelocytic leukemias.

• Acute lymphoblastic leukemia is the leukemia of childhood with highest incidence between the ages of 2 and 6 years.

• Acute lymphoblastic leukemia accounts for 76% of all leukemias diagnosed in children younger than 13 years.

• Children with Down syndrome have an increased risk of leukemia.

• Lymphoblasts will frequently cross the blood-brain barrier, causing neurological involvement.

• In the pediatric age group, children with acute lymphoblastic leukemia have an overall complete remission rate of close to 95%.

A 6-year-old girl presented to her pediatrician with symptoms of fatigue, pallor, bruising, and a pronounced limp. Physical examination revealed moderate splenomegaly, mild lymphadenopathy, and a fever of 101°F CBC results were as follows:

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