[Biological and clinical characteristics of granular lymphocyte proliferation. Review of the literature and personal experience].

The Authors, on the basis of reports from the literature and their personal experience, describe the morphological, immunophenotypic, genotypic and functional features of Large Granular Lymphocytes (LGL). An increased number of the these particular types of lymphocytes may be observed in different pathological conditions and may be interpreted as a reactive process to a possible underlying antigenic stimulation. However, a significant and prolonged increase in LGL's may also identify the existence of a true definite Lymphoproliferative disorder (LGL-PD). It is now well known that phenotypically LGL-PD may be present in two different variants: a CD3+ form, which is more frequent, and a CD3-variant. The former usually is characterized by T-cell receptor monoclonal rearrangement, while CD3- NK cells are frequently polyclonal. However also this latter variant may express clonality and in this case the clinical course is particularly aggressive. Although LGL-PD is a distinct clinical disorder, the Authors underline the extreme variability of the clinical course and the need therefore to adopt a policy of "wait and see" before taking into consideration the choice of different therapeutic options, which are often disappointing and provide remission of only brief duration.