Premalignant Clonal Hematopoietic Proliferations: 2017 Society for Hematopathology/European Association for Haematopathology Workshop Report

Objectives: The 2017 Workshop of the Society for Hematopathology/European Association for Hematopathology aimed to review premalignant clonal hematopoietic proliferations. Methods: The workshop panel reviewed 27 cases of clonal proliferations of indeterminate significance or potential (18 myeloid, nine lymphoid) and rendered consensus diagnoses. Results: Immunophenotyping and genetic studies on peripheral blood, bone marrow, and lymph node samples have led to the incidental detection of small clonal populations in asymptomatic individuals. These premalignant clonal myeloid and lymphoid proliferations include monoclonal gammopathy of uncertain significance, monoclonal B-cell lymphocytosis, in situ follicular neoplasia, in situ mantle cell neoplasia, clonal hematopoiesis of indeterminate potential, and clonal cytopenia of undetermined significance. Conclusions: Current diagnostic criteria for the diagnoses of premalignant clonal hematopoietic proliferations are reviewed and discussed in the context of the cases presented at the workshop. Key Words: CHIP; CCUS; Clonal hematopoiesis; Monoclonal B-cell lymphocytosis; In situ follicular neoplasia; MGUS