Zhihong Hu

CD200 expression in mantle cell lymphoma identifies a unique subgroup of patients with frequent IGHV mutations, absence of SOX11 expression, and an indolent clinical course.

CD200, a marker currently utilized in the diagnosis of B-cell lymphoma, is uniformly positive in chronic lymphocytic leukemia/chronic lymphocytic leukemia, and is usually absent in mantle cell lymphoma. Over a 6 year-period, of 668 mantle cell lymphoma assessed by flow cytometry, CD200 expression was detected in 25 patients (~4%). All 25 patients had bone marrow involvement; however, 11 (44%) patients had no nodal or extranodal disease and belonged to non-nodal leukemic variant mantle cell lymphoma. Morphologically, bone marrow showed an unusual interstitial infiltrative pattern in 14/25 (56%) and small round cells resembling chronic lymphocytic leukemia in 9/25 (36%). CD23 was positive in 19/25 (76%) patients; and SOX11 was only positive in 5/21(24%). All 4 patients tested showed IGHV mutations. With a median follow-up of 23 months, 12/24 (50%) patients were not treated. These clinicopathological features were significantly different from 154 randomly chosen CD200-negative mantle cell lymphoma patients, in SOX11 positivity (24% versus 74%, P<0.0001), CD23 expression (76% versus 8%, P<0.0001), a non-nodal leukemic presentation (44% versus 2%, P<0.001), and therapy requirement (50% versus 92%, P<0.0001). This is the first study to show that CD200 expression in mantle cell lymphoma, though uncommon, identifies a subgroup of mantle cell lymphoma patients with characteristic pathological features, frequent non-nodal leukemic variant, and an indolent clinical course.

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.

Mixed phenotype acute leukemia contains heterogeneous genetic mutations by next-generation sequencing

Mixed phenotype acute leukemia (MPAL) is an uncommon manifestation of acute leukemia. The aim of this study is to further characterize the genetic landscape of de novo cases of MPAL that fulfill the 2016 World Health Organization (WHO) classification criteria for this entity. We identified 14 cases examined by next generation sequencing (NGS) using 28 (n = 10), 53 (n = 3) or 81 (n = 1) gene panels: 7 cases with a B-cell/myeloid (B/My) immunophenotype, 6 T-cell/myeloid (T/My) immunophenotype, and 1 B-cell/T-cell (B/T) immunophenotype. A total of 25 distinct mutations were identified in 15 different genes in 9/14 (64%) patients. FLT3-ITD was the only recurrent mutation in 2 patients. B/My MPAL cases less commonly harbored mutations compared with T/My MPAL cases (43% vs. 100%, p = 0.07). In contrast, B/My MPALs more commonly showed a complex karyotype compared to T/My MPALs (71% vs. 17%, p = 0.1). With NGS and karyotype combined, most (93%) MPAL cases had mutations or cytogenetic abnormalities. With a median follow-up of 12.5 months, there were no significant differences in median overall survival (OS) between patients with B/My or T/My MPAL (17.8 and 6.5 months, respectively, p = 0.81) or between patients with MPAL with versus without gene mutations (6.5 and 13.3 months, respectively, p = 0.86). Our data suggest that the distinguishing cases of MPAL according to immunophenotype has value because the underlying mechanisms of leukemogenesis might differ between B/My and T/My MPAL.

3q26.2/ EVI1 rearrangement is associated with poor prognosis in classical Philadelphia chromosome-negative myeloproliferative neoplasms

Classical Philadelphia chromosome-negative myeloproliferative neoplasms are a group of closely related myeloid disorders with different histologic features and clinical presentations at an early stage, but all later develop into a similar fibrotic stage with variable risk of acute transformation. The significance of 3q26.2/EVI1 rearrangement has been well recognized in acute myeloid leukemia, myelodysplastic syndrome, and chronic myeloid leukemia. However, the clinical importance of 3q26.2/EVI1 rearrangement in classical Philadelphia chromosome-negative myeloproliferative neoplasms is unknown. Here we reported 15 patients with classical Philadelphia chromosome-negative myeloproliferative neoplasms showing 3q26.2 rearrangement, including inv(3)(q21q26.2) (n=6), t(3;21)(q26.2;q22)(n=4), t(3;3)(q21;q26.2)(n=3), inv(3)(q13.3q26.2)(n=1), and t(3;12)(q26.2;p13)(n=1). In addition to 3q26.2 rearrangement, 9 of 15 cases had other concurrent karyotypical abnormalities, including -7/7q- and -5/5q-. There were 8 men and 7 women with a median age of 59 years (range, 35–79 years) at initial diagnosis of myeloproliferative neoplasms: 8 patients had primary myelofibrosis, 4 had polycythemia vera, and 3 had essential thrombocythemia. JAK2 V617F mutation was detected in 8/14 patients, including 4/4 with polycythemia vera. The median interval from the initial diagnosis of myeloproliferative neoplasms to the detection of 3q26.2 rearrangement was 44 months (range, 1–219 months). At time of emergence of 3q26.2 rearrangement, 11 patients were in blast phase and 2 patients had increased blasts (6–19%). Dyspoiesis, predominantly in megakaryocytes, were detected in all patients with adequate specimens at time of 3q26.2 rearrangement. Following 3q26.2 rearrangement, 12 patients received chemotherapy, but none of them achieved complete remission. Of 14 patients with follow-up information, all died with a median overall survival time of only 3 months (range 0–14 months) after the emergence of 3q26.2 rearrangement. In summary, 3q26.2 rearrangement in classical Philadelphia chromosome-negative myeloproliferative neoplasms is associated with other concurrent cytogenetic abnormalities, a rapid disease progression and blast transformation, a poor response to chemotherapy and a dismal prognosis.

TCL-1–positive hematogones in a patient with T-cell prolymphocytic leukemia after therapy

T-prolymphocytic leukemia (T-PLL) is a rare mature T-cell neoplasm characterized by proliferation of prolymphocytes. Most cases involve the T-cell leukemia-1 (TCL1) gene at 14q11.2 resulting in overexpression of TCL-1, which is helpful for distinguishing T-PLL from other T-cell neoplasms. We report a patient with T-PLL whose leukemic cells were positive for TCL-1 by immunohistochemistry but with a normal karyotype. The patient had anti-CD52 antibody therapy for 12 weeks. In a follow-up bone marrow biopsy specimen, numerous TCL-1-positive cells were present, which raised the differential diagnosis of residual T-PLL. However, further immunophenotypic studies confirmed that these cells were hematogones. Therefore a diagnosis of recovering bone marrow was established. The patient underwent stem cell transplant and is now in complete remission. This case demonstrates that hematogones can express TCL-1, and this knowledge is very important for the differential diagnosis in the follow-up marrow of T-PLL patients.

Refractory Hairy Cell Leukemia-Variant

A 67-year-old woman, with a history of hairy cell leukemia-variant (HCL-v), diagnosed 3 years earlier and treated with single-agent rituximab with complete remission, presented with relapsed disease unresponsive to rituximab. A computerized tomography scan showed moderate splenomegaly without lymphadenopathy. Complete blood count and differential: Hgb 13 g/dL, platelets 202 K/lL, WBC 41.7 K/lL (88% lymphocytes, 2% monocytes, and 9% neutrophils). Peripheral blood smear showed numerous lymphocytes with abundant cytoplasm, prominent circumferential cytoplasmic hairy projections, mild nuclear contour irregularities, condensed chromatin; a subset of cells had small nucleoli (Image 1, panels A, B, C). The bone marrow (BM) biopsy showed an interstitial and sinusoidal lymphocytic infiltrate (Image 1, panel D), highlighted by PAX-5 (Image 1, inset, panel D). Aspirate smears demonstrated numerous lymphocytes with morphological features as described in the blood (Image 1, panels E, F, G). The neoplastic cells were also positive for CD20, and DBA.44; and negative for annexin A1, and BRAF. Flow cytometry Fig. 1. Histopathologic and immunophenotypic findings of HCL-v. A–C: Peripheral blood (PB) smear shows lymphocytosis with hairy cytoplasmic projections (Wright–Giemsa; 1,0003). D: Bone marrow (BM) biopsy shows sinusoidal and interstitial lymphoid infiltrate (H&E; 4003) highlighted by PAX-5 (inset, 4003). E–G: BM aspirate smear shows lymphocytes with similar morphology seen in PB smear (Wright–Giemsa; 1,0003). H: Flow cytometry analysis of BM aspirate reveals a clonal B-cell population positive for CD103, CD11c, and negative for CD25.

Blastic plasmacytoid dendritic cell neoplasm associated with chronic myelomonocytic leukemia

![Figure][1] A 64-year-old man presented with progressive skin lesions, which were diagnosed as blastic plasmacytoid dendritic cell neoplasm (BPDCN) and were confirmed with marrow involvement. He received SL-401 chemotherapy but developed persistent monocytosis. A 3-month follow-up bone

Clinicopathologic and molecular features in hairy cell leukemia-variant: single institutional experience

Hairy cell leukemia-variant is rare. Only a small number of cases have been reported in the literature with little cytogenetic or molecular data available. In this study, we describe the clinicopathologic and genetic features of 23 patients with hairy cell leukemia-variant (16 men and 7 women) with a median age of 70 years. Most patients had splenomegaly (90%), leukocytosis (77%), and lymphocytosis (82%); no patients had monocytopenia. Histologically, the bone marrow biopsy specimens showed a mixed pattern of predominantly interstitial and lesser intrasinusoidal infiltration by leukemic cells. In bone marrow aspirate smears most cells had villous cytoplasmic features and a small nucleolus. We describe unusual sites of hairy cell leukemia-variant involvement in 4 patients, including brain, omentum, terminal ileum, and skin at the time of initial presentation. Immunophenotyping showed monotypic B-cells positive for pan B-cell antigens, CD11c, and CD103, and negative for CD25 and annexin A1. Conventional cytogenetic or fluorescence in situ hybridization analysis showed deletions of 17p13/TP53 and 11q22/ATM gene in 5/12 (42%) and 2/9 (22%) cases, respectively. Sequencing of the variable region of IGVH showed mutations (>2% deviation from germline) in 40% of the cases assessed. MAP2K1 mutation (p.C121S) was seen in 1 of 14 (7%) patients tested. No BRAF V600E mutations were detected. The patients were treated in a heterogeneous manner, but most often with therapies designed for classical hairy cell leukemia and the 5-year overall survival was 84%. In summary, hairy cell leukemia-variant exhibits a heterogeneous spectrum of clinical, morphologic, immunophenotypic, and genetic features that may overlap with classic hairy cell leukemia and other hairy cell-like B-cell neoplasms. A subset of patients can have an aggressive clinical course. In our experience MAP2K1 mutations are uncommon in this disease.

3q26/EVI1 rearrangement in myelodysplastic/myeloproliferative neoplasms: An early event associated with a poor prognosis

3q26.2/EVI1 rearrangements resulting in EVI1 overexpression play an important role in leukemogenesis and are associated with treatment resistance and a poorer prognosis in patients with acute myeloid leukemia, myelodysplastic syndrome, chronic myeloid leukemia and BCR-ABL negative myeloproliferative neoplasms. In this study, we aim to explore the clinicopathological features of myelodysplastic/myeloproliferative (MDS/MPN) neoplasms with 3q26.2/EVI1 rearrangements and determine the potential impact of these cytogenetic abnormalities on treatment response and survival. The study group included 12 cases of MDS/MPN with 3q26.2 rearrangements detected by conventional karyotyping. There were 7 men and 5 women with a median age of 67 years (range, 51-79 years) at time of initial MDS/MPN diagnosis. Ten cases were classified as chronic myelomonocytic leukemia (CMML) and 2 were MDS/MPN, unclassifiable. Among CMML cases, 5 (50%) were proliferative type and 5 (50%) were dysplastic type. Based on blast counts, these 10 CMML were: CMML-0 (n = 2), CMML-1 (n = 3), and CMML-2 (n = 5). Eleven (92%) patients had 3q26 rearrangements at the initial diagnosis. Inv(3)(q21q26.2) was most common, identified in 7(58%) patients, followed by t(3;21)(q26.2;q22) in 2 patients and 1 patient each with t(3;3)(q21;q26.2), t(2;3)(p21;q26-27), and t(3;6)(q26.2;q26). Six (50%) patients had 3q26.2 rearrangements as a sole cytogenetic abnormality and 6 (50%) patients had additional cytogenetic abnormalities. Molecular studies revealed DNMT3A mutations in all 3 patients assessed and RAS mutations in 2 of 8 (25%) patients. No mutations in ASXL1 (n = 3), TET2 (n = 3), FLT3 ITD/D835 (n = 10), and CEBPA (n = 7) were detected. Most patients received hypomethylating agent based chemotherapy. The median follow-up was 11.5 months (range, 1.5-24 months) and at time of last follow-up, 11 (92%) died with a median survival of 13.4 months (range, 1.5-24 months). The only patient alive had a relatively short follow-up of 2.4 months and showed disease progression at the last visit. In conclusion, 3q26.2/EVI1 rearrangements are a rare event and usually present at time of initial diagnosis in MDS/MPN. The presence of 3q26.2/EVI1 rearrangements in MDS/MPN is associated with rapid disease progression, poor response to treatment, and a poor prognosis.

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.