Leukemia of early infancy. Early B-cell lineage associated with t(4:11)

A case of infantile acute leukemia associated with translocation t(4:11)(q21:q23) is reported. This leukemia has a very poor prognosis, and this patient survived for only 9 months. The blast cell morphology was L1/L2 according to the FAB classification and showed a lymphoid appearance on transmission electron microscopy. The histochemical stains showed a pattern of periodic acid-Schiff positivity and variable alpha-naphtyl acetate staining. The cells were TdT-positive and surface-marker phenotyping was positive for Ia-like and B4 antigens but negative for CALLA, T-cell markers, myelocyte and monocyte markers. The leukemic cells represent a frozen state of a very early precursor, corresponding to the earliest recognizable stage of the B-cell lineage. This observation may contribute to the controversion regarding the cell origin of this unique leukemia associated with t(4:11), lymphatic versus null cell, early myeloid, or mixed, and points to the possibility of a very early B-cell lineage leukemia.