Extramedullary Manifestations of Myeloid Neoplasms

Objectives: This session of the 2013 Society of Hematopathology/European Association for Haematopathology workshop focused on extramedullary manifestations of myeloid neoplasms. Methods: We divided the submitted cases into four subgroups: (1) isolated myeloid sarcoma (MS); (2) MS with concurrent acute myeloid leukemia (AML), with a focus on karyotypic and molecular findings; (3) extramedullary relapse of AML, including relapse in the posttransplant setting; and (4) blast phase/transformation of a myeloproliferative neoplasm or chronic myelomonocytic leukemia. Results: Establishing a diagnosis of isolated MS requires a high index of suspicion and use of immunophenotypic methods. Recurrent cytogenetic abnormalities or gene mutations that occur in MS mirror those known to occur in AML. Conclusions: In the era of targeted therapy and sophisticated risk stratification, every attempt must be made to perform a complete workup on MS cases (or concurrent AML) since the diagnosis of MS, in itself, is no longer adequate for patient management. Cases of blastic plasmacytoid dendritic cell neoplasm were also included and discussed in this session.