Erythroleukemia in a child: value of immunocytochemistry and transmission electron microscopy in its diagnosis.

A 4 1/2-year-old girl presented with erythroleukemia (EL) that mimicked acute lymphocytic leukemia (ALL). The diagnosis was established with transmission electron microscopy (TEM) and immunocytochemical staining for hemoglobin. Erythroleukemia may present in childhood and may require TEM and immunocytochemistry to make the diagnosis. The correct diagnosis is extremely important since EL has a much poorer prognosis and requires entirely different therapy. Therefore, it is most important to consider EL in those cases of ALL in which the data are not clear-cut and in which the patient fails to respond.