Determination of Early T-cell Precursor Acute Lymphoblastic Leukemia- A Neoplasm with Dual Lineage Phenotype

Early T-cell Precursor Acute Lymphoblastic Leukemia (ETP-ALL) is a subtype of T-ALL/LBL which is derived from thymic cells at the early T-cell precursor (ETP) differentiation stage that have the potential to differentiate into multiple lineages, including lymphoid and myeloid. ETP-ALL accounts for 15% of childhood T-ALL and 10-30% of adult T-ALL. It has characteristic immunophenotypic expression of CD7, a lack of CD1a and CD8, weak expression of CD5 (with <75% positive blasts), and positive expression of one or more stem cell or myeloid markers including CD117, HLADR, CD13, CD33, CD11b, or CD65.ETP-ALL is identified by a well defined gene expression signature including DNMT3A and FAT3 mutations. We here in report two cases of ETP-ALL with brief review of literature.