Molecular Pathology of Myeloid Neoplasms Molecular Pattern Recognition

Myeloid neoplasms encompass a diverse spectrum of hematopoietic malignancies that are all derived from common myeloid progenitor stem cells that accumulate sequential molecular genetic alterations to confer a survival and/or growth advantage. The broad categories are the "chronic" myeloid neoplasms, including myelodysplastic syndromes/neoplasms (MDS), myeloproliferative neoplasms (MPN), MDS/MPN overlap syndromes, and mast cell neoplasms, and the "acute" presentation of myeloid neoplasms that manifests either as "de novo" acute myeloid leukemia (AML) or the leukemic progression of any of the chronic myeloid neoplasms (resulting in secondary AML, s -AML). These main categories, as defined by the World Health Organization monograph on hematopoietic neoplasms (WHO 5 th edition), are summarized in Fig. 1 . 1 Despite the discrete diagnostic categories, the molecular genetic underpinnings of all these entities are highly overlapping and complex such that no single mutation or set of mutations is entirely specific to an entity. However, the myeloid mutational patterns can be encompassed within a simple framework presented as follows.