PDGFRB-rearranged T-lymphoblastic leukemia/lymphoma occurring with myeloid neoplasms: the missing link supporting a stem cell origin.

Abstract

The 2008 WHO classification scheme of hematolymphoid neoplasms recognizes a category of myeloid and lymphoid neoplasms (MLNs) with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR1.1 The postulated cell of origin for PDGFRA or FGFR1-rearranged diseases is a pluripotent progenitor capable of giving rise to myeloid neoplasms (myeloproliferative neoplasms and acute leukemias) and to lymphoblastic leukemia/lymphoma. Historically, PDGFRB translocations have not been associated with malignancies of the lymphoid lineage. Myeloid neoplasms with abnormalities of PDGFRB have been described to have hematologic features of chronic myelomonocytic leukemia (CMML), sometimes with eosinophilia, or as various other myeloproliferative and/or myelodysplastic neoplasms.2 In recognition of this distinction, the classification scheme designates specific categories of “MLNs” with PDGFRA and FGFR1 rearrangement, but omits the word “lymphoid” from the PDGFRB-associated entity.1 To call attention to the rare occurrence of lymphoid and mixed MLNs with abnormalities of PDGFRB, we present the clinical and pathological details of 2 cases.