A case of an unusual lineage switch in late relapse ALL—is it actually a secondary leukemia?

Abstract

Acute lymphoblastic leukemia (ALL) is a malignant disease of lymphoid precursors. According to immunophenotype, it is further subdivided into precursor B cell ALL and precursor T cell ALL, with precursor B cell ALL being much more common both in children and adults. Lineage switch from one lymphoid lineage to another during the course of the disease is extremely rarely reported. Here, we describe a case of a child who initially presented as a precursor BALL but 15 years later and after two successfully treated relapses of the original ALL presented with early T cell precursor leukemia. Although it was considered as a relapse, it could be interpreted as a case of secondary leukemia, which can be explained as a consequence of treatment as well as a constitutional feature of an individual. Also, it draws attention to the possibility that hematopoietic cells, and in that context also leukemic cells, are much more plastic and capable of reprogramming than previously thought.

A paradigm shift: lineage switch from T-ALL to B/myeloid MPAL

“…Relapse in childhood acute leukemia usually occurs within 2 years and is thought to arise from the same clone as that at the initial presentation. Late relapse may indicate a completely new clone, which is characteristic of secondary leukemia and associated with a prior history of cytotoxic therapy [12].…”

“…Relapse in childhood acute leukemia usually occurs within 2 years and is thought to arise from the same clone as that at the initial presentation. Late relapse may indicate a completely new clone, which is characteristic of secondary leukemia and associated with a prior history of cytotoxic therapy [ 12 ]. The presence of therapy-related myeloid neoplasms (t-MNs) is a late effect of chemotherapy (alkylating agents/topoisomerase II inhibitors) and/or radiation after the treatment of a primary disease (post-transplant lymphoproliferative disorders following solid organ transplantation) [ 13 ].…”