Review Question - QID 217225

This young patient who presents with fever, fatigue, petechiae, and night sweats most likely has acute B-cell lymphoblastic leukemia given the finding of an abnormal population of TdT+, CD10+, and CD19+ cells on flow cytometry.

Acute lymphoblastic leukemia (ALL) is a form of acute leukemia caused by the proliferation of lymphoid precursor cells. ALL occurs primarily in children under 15 years of age. Patients will present primarily with constitutional symptoms such as fever and night sweats due to unregulated proliferation of either B or T cell precursors. In addition, crowding of bone marrow often leads to bone marrow failure so patients may also have symptoms of anemia and thrombocytopenia such as anemia, bleeding, and petechiae. The subtypes of ALL include B-cell ALL, which would be seen on flow cytometry as TdT+, CD10+, and CD19/20+ cells, and T-cell ALL, which would be seen on flow cytometry as TdT+, CD2+, and CD3+ cells.

Capria et al. review the current evidence surrounding the diagnosis and treatment of patients with ALL. They find that increased knowledge of molecular profiling of the neoplastic cells has allowed for more targeted treatment of this disease.

Incorrect Answers:
Answer 2: Acute myelogenous leukemia may also present with fever, night sweats, anemia, and thrombocytopenia; however, this disease typically occurs in patients over the age of 60 and would not have cells with lymphocytic markers (TdT). Instead, some subtypes such as acute promyelocytic leukemia present with Auer rods on blood smear and are myeloperoxidase positive.

Answer 3: Chronic lymphocytic leukemia may also have increased cells with lymphocytic markers such as TdT, CD10, and CD19; however, this disease often presents asymptomatically in patients over the age of 60. The characteristic finding of this disease is smudge cells on a peripheral blood smear.

Answer 4: Chronic myeloid leukemia may also present with fever, night sweats, and fatigue; however, this disease would have cells from the myeloid rather than the lymphoid lineages. The characteristic molecular finding in this disease is the 9;22 translocation resulting in the "Philadelphia chromosome."

Answer 5: Hairy cell leukemia may also present with pancytopenia as well as fever and night sweats; however, this disease occurs primarily in older patients between the ages of 50-60. Cells in this disease may also have B-cell markers such as CD10 and CD19; however, the characteristic finding in this disease is positive staining for tartrate-resistant acid phosphatase.

Bullet Summary:
Acute lymphoblastic leukemia presents in children under 15 years old and with positive staining for lymphoid cell markers such as TdT, CD10, and CD19.