Prolymphocytic leukaemia of B- and T-cell subtype: a state-of-the-art paper

A Novel Treatment With Obinutuzumab-Chlorambucil in a Patient With B-Cell Prolymphocytic Leukemia: A Case Report and Review of the Literature

We report the case of a patient with B-cell prolymphocytic leukemia who was successfully treated with the novel humanized monoclonal antibody obinutuzumab. This patient was previously treated with the combination of rituximab and bendamustine and had recurrent infusion reactions. Her treatment with rituximab and bendamustine was discontinued when she developed disease progression after 3 cycles of therapy. She was then treated with obinutuzumab 1000 mg on day 1 of every cycle and chlorambucil 0.5 mg/kg on days 1 and 15 every 28 days to which she had greater tolerability. After 4 cycles of treatment, she had resolution of her clinical symptoms, massive splenomegaly, and normalization of her white blood cell count.

SAMHD1 is recurrently mutated in T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is an aggressive malignancy with a median survival of the patients of less than two years. Besides characteristic chromosomal translocations, frequent mutations affect the ATM gene, JAK/STAT pathway members, and epigenetic regulators. We here performed a targeted mutation analysis for 40 genes selected from a RNA sequencing of 10 T-PLL in a collection of 28 T-PLL, and an exome analysis of five further cases. Nonsynonymous mutations were identified in 30 of the 40 genes, 18 being recurrently mutated. We identified recurrently mutated genes previously unknown to be mutated in T-PLL, which are SAMHD1, HERC1, HERC2, PRDM2, PARP10, PTPRC, and FOXP1. SAMHD1 regulates cellular deoxynucleotide levels and acts as a potential tumor suppressor in other leukemias. We observed destructive mutations in 18% of cases as well as deletions in two further cases. Taken together, we identified additional genes involved in JAK/STAT signaling (PTPRC), epigenetic regulation (PRDM2), or DNA damage repair (SAMHD1, PARP10, HERC1, and HERC2) as being recurrently mutated in T-PLL. Thus, our study considerably extends the picture of pathways involved in molecular pathogenesis of T-PLL and identifies the tumor suppressor gene SAMHD1 with ~20% of T-PLL affected by destructive lesions likely as major player in T-PLL pathogenesis.

Small Cell Variant of T-Cell Prolymphocytic Leukemia with Acquired Palmoplantar Keratoderma and Cutaneous Infiltration

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive post-thymic malignancy that is characterized by the proliferation of small- to medium- sized prolymphocytes. The classic clinical features of T-PLL are lymphocytosis, lymphadenopathy, hepatosplenomegaly, and skin lesions. Skin involvement varies clinically from diffuse infiltrated erythema. Infiltration is localized to the face and ears, nodules, and erythroderma. We present a case of small cell variant of T-PLL in a patient who presented with unusual cutaneous manifestations of acquired palmoplantar keratoderma (PPK) followed by diffuse erythematous infiltrated papules and plaques involving the trunk. When the etiology of acquired PPK is not clear, the physician should consider the possibility of an underlying malignant disease. In this case, the diagnosis of T-PLL was subsequently confirmed by laboratory and cytological findings, as well as by the immunophenotyping of leukemic cells in skin biopsy. Since paraneoplastic acquired PPK may be the initial evident sign of malignancy, the physician's awareness of this manifestation may be crucial for early diagnosis and treatment. Our case emphasizes the importance of accurate evaluation of skin lesions and early skin biopsy in the diagnosis of some hematological malignancies.

Genetic characterization of T-PLL reveals two major biologic subgroups and JAK3 mutations as prognostic marker

T-cell prolymphocytic leukemia (T-PLL) is a rare post-thymic T-cell neoplasm with aggressive clinical course and short overall survival. So far, due to the rareness of this disease, genetic data are available only from individual cases or small cohorts. In our study, we aimed at performing a comprehensive cytogenetic and molecular genetic characterization of T-PLL comprising the largest cohort of patients with T-PLL analyzed so far, including correlations between the respective markers and their impact on prognosis. Genetic abnormalities were found in all 51 cases with T-PLL, most frequently involving the TCRA/D locus (86%). Deletions were detected for ATM (69%) and TP53 (31%), whereas i(8)(q10) was observed in 61% of cases. Mutations in ATM, TP53, JAK1, and JAK3 were detected in 73, 14, 6, and 21% of patients, respectively. Additionally, BCOR mutations were observed for the first time in a lymphoid malignancy (8%). Two distinct genetic subgroups of T-PLL were identified: A large subset (86% of patients) showed abnormalities involving the TCRA/D locus activating the proto-oncogenes TCL1 or MTCP1, while the second group was characterized by a high frequency of TP53 mutations (4/7 cases). Further, analyses of overall survival identified JAK3 mutations as important prognostic marker, showing a significant negative impact.

Pathology of T-cell lymphomas: diagnosis and biomarker discovery

T-cell lymphomas are a group of predominantly rare hematologic malignancies that tend to recapitulate different stages of T-cell development, in a similar way that B-cell lymphomas do. As opposed to B-cell lymphomas, the understanding of the biology and the classification of T-cell lymphomas are somewhat rudimentary, and numerous entities are still included as 'provisional categories' in the World Health Classification of hematolopoietic malignancies. A relevant and useful classification of these disorders have been difficult to accomplish because of the rarity nature of them, the relative lack of understanding of the molecular pathogenesis, and their morphological and immunophenotypical complexity. Overall, T-cell lymphomas represent only 15 % of all non-Hodgkin lymphomas. This review is focused on addressing the current status of the categories of mature T-cell leukemias and lymphomas (nodal and extranodal) using an approach that incorporates histopathology, immunophenotype, and molecular understanding of the nature of these disorders, using the same philosophy of the most recent revised WHO classification of hematopoietic malignancies.

The MEC1 and MEC2 lines represent two CLL subclones in different stages of progression towards prolymphocytic leukemia

The EBV carrying lines MEC1 and MEC2 were established earlier from explants of blood derived cells of a chronic lymphocytic leukemia (CLL) patient at different stages of progression to prolymphocytoid transformation (PLL). This pair of lines is unique in several respects. Their common clonal origin was proven by the rearrangement of the immunoglobulin genes. The cells were driven to proliferation in vitro by the same indigenous EBV strain. They are phenotypically different and represent subsequent subclones emerging in the CLL population. Furthermore they reflect the clinical progression of the disease. We emphasize that the support for the expression of the EBV encoded growth program is an important differentiation marker of the CLL cells of origin that was shared by the two subclones. It can be surmised that proliferation of EBV carrying cells in vitro, but not in vivo, reflects the efficient surveillance that functions even in the severe leukemic condition. The MEC1 line arose before the aggressive clinical stage from an EBV carrying cell within the subclone that was in the early prolymphocytic transformation stage while the MEC2 line originated one year later, from the subsequent subclone with overt PLL characteristics. At this time the disease was disseminated and the blood lymphocyte count was considerably elevated. The EBV induced proliferation of the MEC cells belonging to the subclones with markers of PLL agrees with earlier reports in which cells of PLL disease were infected in vitro and immortalized to LCL. They prove also that the expression of EBV encoded set of proteins can be determined at the event of infection. This pair of lines is particularly important as they provide in vitro cells that represent the subclonal evolution of the CLL disease. Furthermore, the phenotype of the MEC1 cells shares several characteristics of ex vivo CLL cells.

Splenic lymphoid subsets with less well-recognized phenotypes mimic aberrant antigen expression

OBJECTIVES

Flow cytometry can assist in the diagnosis of lymphoma by identifying aberrant antigen expression. Recognition of aberrancy requires knowledge of the phenotype of normal lymphoid cells.

METHODS

Lymphoid subsets were characterized in 20 spleens removed for traumatic rupture, using 8-color flow cytometry.

RESULTS

Normal variation in splenic lymphoid subsets was highlighted and several well-recognized subsets were identified: CD5+ B cells (20/20 specimens), CD7- T cells (20/20), and CD3 brightγδT cells (16/20). In addition, less well-recognized lymphoid subsets that resemble those described in lymphoma were identified in all specimens: CD5- T cells (4.5 ± 5.1% of T cells), CD2- natural killer (NK) cells (38 ± 7% of NK cells), and CD7dim+ NK cells. Similar populations were identified in 20 control peripheral blood specimens, where they represented a smaller proportion of total lymphoid cells.

CONCLUSIONS

Familiarity with the phenotype of normal lymphoid subsets can help prevent misinterpreting flow cytometric data. Furthermore, in the context of neoplastic cells, the phenotype may suggest expanded normal subsets rather than aberrant antigen expression.

CD200 has an important role in the differential diagnosis of mature B-cell neoplasms by multiparameter flow cytometry

BACKGROUND

Multiparameter flow cytometry is a useful tool for the diagnostic evaluation of mature B-cell neoplasms (MBN). Recently, it has been shown that CD200 may improve the distinction between chronic lymphocytic leukemia (CLL; CD200+) and mantle cell lymphoma (MCL; CD200-), but the role of CD200 expression in atypical CLL and other MBN remains to be established.

METHODS

To address this issue, we investigated the expression of CD200 in 159 consecutive cases of MBN.

RESULTS

CD200 was strongly expressed in CLL and was revealed to be an excellent marker to distinguish CLL from MCL, even in cases of atypical CLL. However, lack of CD200 was not an exclusive finding of MCL, being also observed in other MBNs. Furthermore, CD200 was highly expressed in hairy cell leukemia, being useful in the differential diagnosis of lymphomas with villous lymphocytes. Herein, we propose an algorithm to classify CD5+ MBNs based on the expression of CD200, CD11c, heavy chain immunoglobulins, and Matutes score.

CONCLUSIONS

These results expand the understanding of the CD200 expression in MBNs, giving further support for the inclusion of this marker in the routine investigation by flow cytometry.

B-cell prolymphocytic leukemia and hairy cell leukemia: new advances in biology and treatment

SUMMARY B-cell prolymphocytic leukemia and hairy cell leukemia are mature lymphoid neoplasms recognized by WHO classification as distinct entities. The diagnosis relies on a constellation of clinical and laboratory features. B-cell prolymphocytic leukemia is a rare disease that lacks a genetic signature and represents a challenge to clinicians, due to the limited information on its pathogenesis, the difficulty of setting up prospective clinical trials and its refractoriness to treatments used in other chronic lymphoid neoplasms. By contrast, major advances have taken place in the understanding of the pathogenesis of hairy cell leukemia, as well as in the therapeutic armamentarium available for this disease. In this review, data will be presented on the natural history, pathogenesis, diagnosis and current therapies for these two leukemias.

Cerebriform variant type of T cell prolymphocytic leukemia with complex karyotype including an additional segment at 1p36.1

We describe two patients with T cell prolymphocytic leukemia (T-PLL) who exhibited the same complex karyotype, including an additional segment at 1p36.1. One presented with secondary progression following an initial stable clinical course, and the other with typically progressive disease. Features of the cerebriform variant were identified in the peripheral blood of both patients. Aggressive symptoms, such as lymphocytosis, lymphadenopathy, pleural effusion, cutaneous involvement and hepatosplenomegaly, developed during the progressive phases. Levels of serum soluble interleukin 2 receptor increased when symptoms worsened. These patients did not have the karyotypic 14q11 abnormality and trisomy 8q that are features of non-Japanese patients. The prognoses of these patients were poor; one survived for 2 months and the other survived for 10 months after progression. A chromosomal abnormality may occur in other types of aggressive T-PLL, particularly when extramedullary infiltration is a feature.

Pediatric T-cell prolymphocytic leukemia with an isolated 12(p13) deletion and aberrant CD117 expression

T-cell Prolymphocytic leukemia (T-PLL) is a rare post-thymic T-cell malignancy that follows an aggressive clinical course. The classical presentation includes an elevated white blood cell (WBC) count with anemia and thrombocytopenia, hepatosplenomegaly, and lymphadenopathy. T-PLL is a disease of the elderly and to our knowledge it has never been described in the pediatric age group. We report a case of T-PLL in a 9 year old male who was initially diagnosed with T-cell acute lymphoblastic lymphoma (ALL), the diagnosis was later refined to T-PLL following additional analysis of bone marrow morphology and immunophenotype. Two unusual findings in our patient included CD117 expression and an isolated chromosomal 12(p13) deletion. The patient failed to respond to standard ALL induction chemotherapy, but achieved complete remission following treatment with a fludarabine and alemtuzumab-based regimen.

A case report of T cell prolymphocytic leukemia and Kaposi sarcoma and a review of T cell prolymphocytic leukemia

T cell prolymphocytic leukemia (T-PLL) is a rare mature T cell lymphoproliferative disease. It has been associated with an aggressive course, a poor response to conventional chemotherapy and a short median survival. Here we present a rare case of concurrent T-PLL and Kaposi sarcoma who achieved a complete hematologic and cytogenetic remission after a very short course of treatment with alemtuzumab. A review of T-PLL was done. In this review, clinical features, laboratory features and current therapeutic strategies of T-PLL are presented.

TCL1A gene involvement in T-cell prolymphocytic leukemia in Japanese patients

T-cell prolymphocytic leukemia (T-PLL) is a rare type of peripheral T-cell leukemia. In this study, we examined the clinical and biological characteristics of 11 Japanese patients with T-PLL. Median age was 74 years, with male predominance. Median lymphocyte frequency was 85.3% in blood. Physical characteristics were splenomegaly (36.4%), tiny lymph adenopathy (63.6%), skin lesion (9.1%) and pleural effusion (27.3%). Median survival was 30.1 months, despite treatment with various chemotherapeutic modalities. Although complex chromosomal abnormalities were observed in 5 of 11 cases (45.5%), typical 14q32 and Xq28 abnormalities were not detected. TCL1A mRNA expression was observed in 6 of 11 cases (54.5%) on real-time quantitative PCR. In 5 of these 6 cases, flow cytometric analysis and/or immunohistochemistry confirmed the expression of TCLA1 protein. Split signals for the TCL1 region on fluorescence in situ hybridization confirmed rearrangement in 3 out of 7 cases evaluated. These cases corresponded to cases that were positive for TCL1A expression, suggesting that rearrangement of the TCL1 region induced high expression of TCL1A gene. In summary, a substantial number of T-PLL cases in Japan had abnormal expression of TCL1A, probably due to rearrangement of TCL1 region. Expression and/or rearrangement of TCL1A may, therefore, be a useful marker for diagnosing T-PLL, regardless of chromosomal abnormalities.

Lack of TIR8/SIGIRR triggers progression of chronic lymphocytic leukemia in mouse models

Inflammation is involved in the initiation and progression of several chronic lymphoid malignancies of B-cell type. Toll-like receptors (TLR) are transmembrane inflammatory receptors that on recognition of pathogen-associated molecular patterns trigger an innate immune response and bridge the innate and adaptive immune response by acting as costimulatory signals for B cells. Fine tuning of TLR and IL-1R-like (ILR) activity is regulated by TIR8 (SIGIRR), a transmembrane receptor of the TLR/ILR family which inhibits other family members. To test the hypothesis that TLR and/or ILR may play a role in the natural history of chronic B-cell tumors, we crossed Eμ-TCL1 transgenic mice, a well established model of chronic lymphocytic leukemia (CLL), with mice lacking the inhibitory receptor TIR8 that allow an unabated TLR-mediated stimulation. We here report that in the absence of TIR8 the appearance of monoclonal B-cell expansions is accelerated and mouse life span is shortened. The morphology and phenotype of the mouse leukemic expansions reproduce the progression of human CLL into an aggressive and frequently terminal phase characterized by the appearance of prolymphocytes. This study reveals an important pathogenetic implication of TLR in CLL development and progression.

How I diagnose and treat splenic lymphomas

The incidental finding of an isolated splenomegaly during clinical assessment of patients evaluated for unrelated causes has become increasingly frequent because of the widespread use of imaging. Therefore, the challenging approach to the differential diagnosis of spleen disorders has emerged as a rather common issue of clinical practice. A true diagnostic dilemma hides in distinguishing pathologic conditions primarily involving the spleen from those in which splenomegaly presents as an epiphenomenon of hepatic or systemic diseases. Among the causes of isolated splenomegaly, lymphoid malignancies account for a relevant, yet probably underestimated, number of cases. Splenic lymphomas constitute a wide and heterogeneous array of diseases, whose clinical behavior spans from indolent to highly aggressive. Such a clinical heterogeneity is paralleled by the high degree of biologic variation in the lymphoid populations from which they originate. Nevertheless, the presenting clinical, laboratory, and pathologic features of these diseases often display significant overlaps. In this manuscript, we present our approach to the diagnosis and treatment of these rare lymphomas, whose complexity has been so far determined by the lack of prospectively validated prognostic systems, treatment strategies, and response criteria.

The PARP inhibitor olaparib induces significant killing of ATM-deficient lymphoid tumor cells in vitro and in vivo

The Ataxia Telangiectasia Mutated (ATM) gene is frequently inactivated in lymphoid malignancies such as chronic lymphocytic leukemia (CLL), T-prolymphocytic leukemia (T-PLL), and mantle cell lymphoma (MCL) and is associated with defective apoptosis in response to alkylating agents and purine analogues. ATM mutant cells exhibit impaired DNA double strand break repair. Poly (ADP-ribose) polymerase (PARP) inhibition that imposes the requirement for DNA double strand break repair should selectively sensitize ATM-deficient tumor cells to killing. We investigated in vitro sensitivity to the poly (ADP-ribose) polymerase inhibitor olaparib (AZD2281) of 5 ATM mutant lymphoblastoid cell lines (LCL), an ATM mutant MCL cell line, an ATM knockdown PGA CLL cell line, and 9 ATM-deficient primary CLLs induced to cycle and observed differential killing compared with ATM wildtype counterparts. Pharmacologic inhibition of ATM and ATM knockdown confirmed the effect was ATM-dependent and mediated through mitotic catastrophe independently of apoptosis. A nonobese diabetic/severe combined immunodeficient (NOD/SCID) murine xenograft model of an ATM mutant MCL cell line demonstrated significantly reduced tumor load and an increased survival of animals after olaparib treatment in vivo. Addition of olaparib sensitized ATM null tumor cells to DNA-damaging agents. We suggest that olaparib would be an appropriate agent for treating refractory ATM mutant lymphoid tumors.

[Successful treatment of B-cell prolymphocytic leukemia (B-PLL) with FCR-Lite (fludarabine, cyclophosphamide, rituximab) protocol]

B-cell prolymphocytic leukemia (B-PLL) is a rare disorder characterized by marked lymphocytosis in the peripheral blood, matured lymphocytic infiltration in the bone marrow and splenomegaly. It has a distinct immunophenotype (CD19, CD20, CD22, FMC7, intensive surface immunoglobulin positivity) which helps to differentiate from other lymphoproliferative malignancies. It has a poor prognosis and its treatment is unsettled. The authors present a case of a patient with typical B-PLL treated with FCR-Lite (fludarabine, cyclophosphamide, rituximab) protocol achieving complete hematological (and immunophenotypic) remission. The treatment was well tolerated. Neither major infective complication nor tumor lysis syndrome was observed. According to the author's experience the FCR-Lite protocol can not only be used in patients with CLL but it also can be effective in patients with B-PLL. No clinical experience has been reported yet in the literature with this protocol.

Pathobiology of mature T-cell lymphomas

Mature T- and natural killer (NK)-cell neoplasms are relatively rare forms of leukemia/lymphoma. The diagnosis of these entities is often difficult, necessitating extensive immunophenotypic, molecular, and genetic testing. Despite the accumulating information on the pathobiology of these neoplasms, in many cases the prognosis remains poor. This article presents an updated view of the morphologic, immunophenotypic, genetic, and molecular characteristics of the mature T- and NK-cell neoplasms. For a better understanding of this complex topic, the development of normal T and NK cells is briefly discussed. The presentation of the characteristic features of the neoplasms in the 2008 World Health Organization classification of hematopoietic neoplasms includes advances in the understanding of the pathobiology of each diagnostic category.