Acute lymphoblastic leukemia with e1a3 BCR/ABL fusion protein. A report of two cases.

B Acute Lymphoblastic leukemia (B-ALL) with Philadelphia chromosome (Ph') is a neoplasm of lymphoblast committed to the B cell lineage. The clinical presentation of B-ALL Ph'+ is similar to B-ALL, but is more common in adults than in children. The e1a3 rare variant is produced by the fusion of BCR exon 1 to ABL exon 3. The presence of this translocation has been associated with good disease outcome for chronic myeloid leukemia in a very small series of only 5 cases; there is no such evidence for B-ALL. We report two new cases of B-ALL Ph+ with the rare e1a3 fusion transcript. The e1a3 and e1a2 (p190) transcripts have been reported to have a similar molecular weight and probably a similar clinical profile, thus in these cases the presence of e1a3 was associated with extramedullary infiltration and disease acceleration.