T-cell chronic lymphocytic leukemia or small-cell variant of T-cell prolymphocytic leukemia: a historical perspective and search for consensus

Morphology, immunophenotype, and suggested diagnostic criteria of TCL1 family-negative T-prolymphocytic leukemia

OBJECTIVES

We sought to investigate the morphologic and immunophenotypic characteristics of TCL1 family-negative T-cell prolymphocytic leukemia (T-PLL).

METHODS

Twenty cases of TCL1 family-negative T-PLL were studied.

RESULTS

The doubling time of leukemic cells ranged from less than 2 days to more than 5 years, with a median of 5.5 months. Leukemic cells were small to medium-sized, with round to irregular nuclei, variably condensed chromatin, and small amounts of agranular cytoplasm. A visible nucleolus was identified in 11 (55%) cases. Cytoplasmic blebs/protrusions were identified in all cases, but their occurrence was highly variable from case to case. Bone marrow biopsy showed an interstitial pattern in 90% of cases and a diffuse pattern in the remaining 10% of cases. Flow cytometric immunophenotypic analysis showed that the leukemic cells in all cases were CD4 positive; 3 (15%) also showed concurrent CD8 expression. All cases were positive for CD2 and CD5. Surface CD3 and CD7 were positive in 19 of 20 (95%) cases, and all CD3-positive cases expressed the T-cell receptor αβ. Compared with prototypic T-PLL cases, these 2 groups shared many immunophenotypic findings, except CD8 and CD26, both of which were more commonly expressed in prototypic T-PLL cases.

CONCLUSIONS

TCL1 family-negative T-PLL cases have morphologic and immunophenotypic features that are similar to prototypic T-PLL. They are characterized by neoplastic proliferation of small to medium-sized mature T cells with CD4-positive T-cell receptor αβ phenotype. Tumor cells frequently maintain pan-T antigen expression. Recognizing these morphologic and immunophenotypic features will aid in accurately diagnosing this rare subset of T-PLL.

An unusual case of T-cell prolymphocytic leukemia mimicking a cutaneous vasculitis

T-cell prolymphocytic leukemia (T-PLL) is an aggressive post-thymic T-cell malignancy, which accounts for 2% of mature lymphocytic leukemias in adults. Though typically presenting with a brief history of B symptoms, hepatosplenomegaly, and marked lymphocytosis, erythematous or nodular skin rashes involving the trunk or limbs may be seen in 25% to 30% of patients, as well as a purpuric rash in a periorbital distribution. Cutaneous involvement typically presents in the context of patients with an established history of T-PLL, but it can less frequently present as an initial symptom heralding the diagnosis. An unusual case of T-PLL is described, presenting initially as palmoplantar ulcerated nodules with an initial biopsy suggestive of perniosis, followed by rapid progression of dark violaceous and bright red papules throughout the body after initiation of Obinutuzumab. The diagnosis of T-PLL was subsequently fully supported by the clinical, laboratory, cytologic, and immunophenotypic findings. This case highlights the importance of a multidisciplinary team approach to address such rare and atypical presentations.

Whole-exome sequencing identified mutational profile of a case with T-cell chronic lymphocytic leukemia

We believe that our report and further case reports on T-cell chronic lymphocytic leukemia with genetic profile will contribute to the molecular classification of this rare but distinct disease.

Prolymphocytic Leukemia: New Insights in Diagnosis and in Treatment

PURPOSE OF REVIEW

We aimed to produce a comprehensive update on clinical and biological data regarding two rare lymphoid neoplasms, B and T prolymphocytic leukemias, and assess therapeutic management in the light of new molecular insights and the advent of targeted therapies.

RECENT FINDINGS

B cell prolymphocytic leukemia (B-PLL) diagnosis remains challenging in the absence of clear immunophenotypic or cytogenetic signature and overlap with mantle cell lymphoma. New molecular defects have been identified in T cell prolymphocytic leukemia (T-PLL), especially in the JAK STAT pathway. Like in chronic lymphocytic leukemia (CLL), B-PLL treatment depends on the presence of TP53 dysfunction. In T-PLL, alemtuzumab still remains the standard of care. Allogeneic transplantation is the only curable option. Thanks to reduced intensity conditioning regimens, it has become accessible to a larger number of patients. PLL prognosis remains poor with conventional therapies. However, great advances in the understanding of both T- and B-PLL pathogenesis lead to promising new therapeutic agents.

Comparison of karyotyping, TCL1 fluorescence in situ hybridisation and TCL1 immunohistochemistry in T cell prolymphocytic leukaemia

Aims

T cell prolymphocytic leukaemia (T-PLL) is defined as an aggressive T cell leukaemia composed of small to medium-sized lymphocytes with a mature T cell immunophenotype. Most of these cases are known to be associated with inv(14q11q32)/t(14;14)(q11;q32) or rarely t(X;14)(q28;q11). However, T-PLL can show variations in clinical presentation, morphology or immunophenotype that can make a diagnosis of T-PLL challenging. We aim to explore the value of ancillary testing in the diagnosis of T-PLL.

Methods

With this large cohort of 69 patients with T-PLL, we compared the diagnostic utility of conventional cytogenetics, TCL1 rearrangement by fluorescence in situ hybridisation (FISH) and TCL1 expression by immunohistochemistry (IHC).

Results

Conventional karyotyping was performed in all 69 patients and was abnormal in 44 (65%), showing 14q32 abnormalities in 31 (43%) and t(X;14) (MTCP) in 2 (3%). TCL1 rearrangement was assessed by FISH in 26 cases and was positive in 23 (85%). All cases with 14q32 abnormalities shown by karyotype were positive for TCL1 rearrangement by FISH, whereas 12/15 (80%) cases without 14q32 abnormalities were also positive. TCL1 overexpression by IHC was detected in 51/64 (81%), including 40/42 (95%) cases with TCL1/14q32 rearrangement, and 3 cases without, showing a concordance of 89%. TCL1 IHC was negative in both cases with t(X;14)(q28;q11).

Conclusions

Our study shows that TCL1 by IHC is a convenient test, positive in >80% T-PLL. Conventional cytogenetics is insensitive in the detection of 14q32/TCL1 rearrangements but provides more complete information of the chromosomal landscape of T-PLL. FISH for TCL1 rearrangement is very valuable in diagnostic challenging cases.

Prognostic significance of cytogenetic abnormalities in T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is an aggressive mature T-cell neoplasm. The most common cytogenetic abnormality associated with T-PLL is inv(14)(q11.2q32) involving TCL1, but other abnormalities also have been reported. In this study, we correlated cytogenetic abnormalities with clinical outcome in 97 T-PLL patients, including 66 men and 31 women with a median age of 63 years (range, 34-81). Twenty-seven patients had a normal karyotype (NK), one had two chromosomal aberrations, and 69 had a complex karyotype (CK). Patients with a CK had poorer overall survival (OS) than patients with a NK (P = .0016). In the CK group, the most common aberrations involved 14q (n = 45) and 8q (n = 38). Additional deletions of chromosomes 17p, 11q, 6q, 12p, 13q were observed frequently. No individual cytogenetic abnormality impacted OS. Patients with ≥5 aberrations had an OS of 11 months versus 22 months in patients with <5 aberrations (P = 0.0132). Fluorescence in situ hybridization for TCL1 successfully performed in 27 cases showed rearrangement in 8/10 (80%) NK versus 16/17 (94%) CK cases. OS of patients with TCL1 rearrangement and/or 14q aberrations was not significantly different from patients without TCL1 rearrangement and 14q aberrations (P = .3467). Patients with refractory disease showed worse OS in both the NK and CK groups (P = .0014 and P < .0001, respectively), compared with patients who achieved remission but then relapsed. Stem cell transplantation did not appear to improve OS regardless of karyotype complexity. In conclusion, patients with T-PLL often have a CK which is a poor prognostic factor, particularly in patients with ≥5 cytogenetic aberrations.