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 nowestablished 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 À CD8À 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 nextgeneration 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.

Comparison of clinicopathological characteristics between T‐cell prolymphocytic leukemia and peripheral T‐cell lymphoma, not otherwise specified

“…It is possible that the proportion T-PLL-sv in Japan may be relatively higher than in Europe and the United States. 12 In our study, there was no statistical difference in prognosis between T-PLL-sv (N=7) and non-T-PLL-sv ("normal" T-PLL; N=8;…”

“…Although 20%-25% of T-PLL cases are reported to be T-PLL-sv, 12 there were seven cases (46.7%) in our study. It is possible that the proportion T-PLL-sv in Japan may be relatively higher than in Europe and the United States.…”

“…Although 20%‐25% of T‐PLL cases are reported to be T‐PLL‐sv, there were seven cases (46.7%) in our study. It is possible that the proportion T‐PLL‐sv in Japan may be relatively higher than in Europe and the United States . In our study, there was no statistical difference in prognosis between T‐PLL‐sv (N=7) and non‐T‐PLL‐sv (“normal” T‐PLL; N=8; P =.262; Figure ); however, the prognosis of T‐PLL‐sv may be found to be better than that of “normal” T‐PLL if more cases are analyzed.…”

“…If tumor cells were less than twice the size of normal lymphocytes and their nuclei were unremarkable by light microscopy, they were defined as small-cell variant (T-PLL-sv) as previously described. 12 T-cell prolymphocytic leukemia diagnoses were confirmed by analyzing both peripheral blood images and pathological findings of…”

T-Cell Chronic Lymphocytic Leukemia: A Rare Case Report

“…There is also provided a systematic analysis of all previously reported cases of T-PLL-sv as well as four new additional case. [1] A clonal evolution model has been proposed 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. [2] Involvement of the peripheral blood, bone marrow, lymph nodes, liver, spleen, and skin can occur.…”