A 15-year-old boy is complaining of severe headaches; he has a white count of 76.0 x 109/L, platelet count of 55 x 109/L, and a hematocrit of 33%

When a white cell differential is performed, most of the nucleated cells are blasts. They are CD2, CD4, and CD8 positive. What is the most likely diagnosis?

a. Immature-B cell acute lymphoblastic leukemia
b. T-cell acute lymphoblastic leukemia
c. Acute myeloid leukemia without maturation
d. Acute myeloid leukemia with maturation

ANS: B
T-cell acute lymphoblastic leukemia is most often seen in teenage boys with a mediastinal mass, elevated peripheral blast counts, meningeal involvement, and infiltration of extra marrow sites. The blasts commonly mark as CD2, CD4, CD5, and CD8 positive.