title: T-cell chronic lymphocytic leukemia or small-cell variant of T-cell prolymphocytic leukemia: a historical perspective and search for consensus.
abstract: There is a rich history behind the extinct entity 'T-cell chronic lymphocytic leukemia (T-CLL)' and the now-established replacement, small-cell variant of T-cell prolymphocytic leukemia (T-PLL-sv). Herein, we review the history of the events, observations, and discussions that led to this replacement. We also provide a systematic analysis of all previously reported cases of T-PLL-sv as well as our four new additional cases. Despite the higher frequency of a normal karyotype and perhaps an overrepresented CD4(-) CD8(-) immunophenotype among these patients (compared to T-PLL in general) as well as bland morphology (that makes them superficially appear more similar to B-CLL), we argue that the current World Health Organization (WHO)-based classification as T-PLL-sv is adequate and should continue for the time being. Morphologically, T-PLL-sv represents approximately one-fifth of all T-PLL cases. However, morphology alone does not determine the clinical course and should not be the basis for clinical decision making and prognostication. We propose a clonal evolution model in which mature T-cell leukemias classified in the past as T-CLL are perhaps T-PLL diagnosed early in the course of the disease. Future research using next-generation sequencing, comparative genomic hybridization, and molecular array studies, including serial analyses of individual cases over time, is needed to better identify this rarely diagnosed, inherently controversial form of T-cell leukemia.
authors.affiliation: Division of Oncology, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Armin
authors.initials: A
authors.lastname: Rashidi
authors.affiliation: Pathology Sciences Medical Group/Sentara Laboratory Services, Norfolk, VA, USA.
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Fisher
mesh_terms: D000818:Animals; D060965:Clonal Evolution; D006801:Humans; D016130:Immunophenotyping; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D015461:Leukemia, Prolymphocytic, T-Cell / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D012106:Research
keywords: World Health Organization; chronic lymphocytic leukemia; nucleolus; prolymphocytic leukemia; small-cell variant