Early neoplastic lymphoid lesions

The differential diagnosis between neoplastic and reactive lymphoid proliferations is a relatively common situation, which in most cases is resolved using conventional morphological and phenotypic criteria. In the last years, a number of studies have identified different types of lymphoid lesions sharing pathological and molecular features of both benign and malignant processes that are difficult to interpret. A group of these lesions correspond to atypical lymphoid hyperplasias, including follicular hyperplasias, atypical marginal zone hyperplasias, and florid reactive lymphoid hyperplasias of the lower female genital tract in which immunoglobulin light chain restriction with or without clonal IGH rearrangements may be found in some cases. However, these lesions are usually self-limited and do not evolve to an overt lymphoid neoplasia. A second group of lesions are clonal expansions of cells with phenotypic or molecular features of well-defined lymphoid neoplasias, such as chronic lymphocytic leukemias, follicular lymphomas, or mantle cell lymphomas, occurring in otherwise healthy individuals or in the context of reactive lymphoid tissues. In this review, we discuss the criteria to distinguish these lesions from overt lymphomas and the current recommendations for the management of the individuals in which these lesions are found.