Grey zone lymphoid neoplasms with features overlapping between splenic marginal zone lymphoma and hairy cell leukaemia: splenic B-cell lymphoma/leukaemia, unclassifiable

[Histopathological classification of chronic B-lymphoproliferative disorders]

Chronic lymphoproliferative disorders should be classified according to the revised 2016 WHO classification. Biopsies are not mandatory for all chronic lymphoproliferative disorders as blood or bone marrow cytologroachical approach can be sufficient for some lymphoma entities. Diagnostic is based on a multidiscplinary approach taking into account clinical presentation, histopathological, cytological, immunophenotypical features (immunohistochemistry and Flow cytometry) and molecular pattern (translocation by FISH, Mutations landscape by NGS, and genomic abnormalities by CGH array). An important heterogeneity of clinical presentation and prognosis arises within the same lymphoma subtype. Clinical evolution is characterized by relapses, cytological progression and transformation into diffuse large B cell lymphoma, aggressive lymphoma or high-grade lymphomas.