Letters to the Editor 644 normal PB buffy coat DNA (see example in Figure 1b). These marrow (used for MRD evaluation), the actual Quantitative data show that NSA can be variable, dependent on the type of Range for TCRG targets will often be underestimated. sample (bone marrow or peripheral ) and the time point We conclude that the ESG-MRD-ALL guidelines for inter- during or after therapy. pretation of RQ-PCR data appropriately take into account the We next evaluated to what extent this variation in NSA variation in NSA. The guidelines for prevention of false-positive affected the RQ-PCR data interpretation, applying the guidelines MRD data perform well, with less than 2% false-positive results. for prevention of false-positive MRD results as well as the However, our data also clearly indicate that positive results guidelines for preventing false-negative MRD results. In Figures outside the Quantitative Range should always be judged with 2a-c, the data interpreted according to the guidelines for the caution, particularly for samples taken after cessation of therapy prevention of false-negative MRD results are shown. IGH targets and analyzed with Ig gene targets. Preferably, one should aim with NSA in normal PB buffy coat DNA resulted in false-positive for RQ-PCR assays without any NSA, since this will improve the MRD data in about 10% of samples obtained during therapy reliability of the data interpretation. (Figure 2a). However, in samples obtained after cessation of therapy (after week 104) false-positivity could be observed in up VHJ van der Velden, JM Wijkhuijs and JJM van Dongen Department of , Erasmus MC, University Medical to 65% of samples. In one sample the level of NSA even reached Center Rotterdam, Rotterdam, The Netherlands the Quantitative Range of the assay (Figure 2a). False-positive E-mail: [email protected] MRD results were hardly observed for IGH targets without NSA in normal PB buffy coat DNA (Figure 2b) and were less than References 10% for TCRG targets, irrespective of the time-point the sample was taken (Figure 2c). If the guidelines for prevention of false- 1 van der Velden VH, Cazzaniga G, Schrauder A, Hancock J, Bader P, positive MRD results were applied, false-positivity was only Panzer-Grumayer ER et al. Analysis of minimal residual disease by observed for IGH targets that also showed NSA in normal PB Ig/TCR gene rearrangements: guidelines for interpretation of real- buffy coat DNA (Figures 2d and e). This false-positivity was time quantitative PCR data. Leukemia 2007; 21: 604–611. present only in a few samples obtained after induction therapy 2 van der Velden VH, Panzer-Grumayer ER, Cazzaniga G, Flohr T, ( 5%) and in some samples obtained after cessation of therapy Sutton R, Schrauder A et al. Optimization of PCR-based minimal o residual disease diagnostics for childhood acute lymphoblastic (5–15%). leukemia in a multi-center setting. Leukemia 2007; 21: 706–713. Our data are in line with the previously reported changes in 3 van der Velden VHJ, Hochhaus A, Cazzaniga G, Szczepanski T, the cellular composition of the bone marrow during and after Gabert J, van Dongen JJM. Detection of minimal residual disease in therapy (Figures 1c and d).4–6 After induction therapy, there is a hematologic malignancies by real-time quantitative PCR: principles, massive regeneration of precursor B cells, particularly the most approaches, and laboratory aspects. Leukemia 2003; 17: immature CD10 þ TdT þ precursor B cells,4,5 which have 1013–1034. 4 van Wering ER, van der Linden-Schrever BE, Szczepanski T, incomplete IGH (DH–JH) rearrangements but low levels com- Willemse MJ, Baars EA, van Wijngaarde-Schmitz HM et al. 8 plete IGH (VH–JH) gene rearrangements. In contrast, after Regenerating normal B-cell precursors during and after cessation of maintenance therapy the precursor compart- treatment of acute lymphoblastic leukaemia: implications for ment in bone marrow mainly consists of more mature monitoring of minimal residual disease. Br J Haematol 2000; 110: CD10 þ TdTÀ precursor B cells4,5 containing complete IGH 139–146. gene rearrangements.8 Consequently, increased NSA levels of 5 van Lochem EG, Wiegers YM, van den Beemd R, Hahlen K, van Dongen JJM, Hooijkaas H. Regeneration pattern of precursor-B-cells IGH (VH–JH) rearrangements can particularly be observed during in bone marrow of acute lymphoblastic leukemia patients depends the post-maintenance treatment regeneration phases. T cells on the type of preceding chemotherapy. Leukemia 2000; 14: show limited changes in their frequency in bone marrow 688–695. samples; they are particularly present in bone marrow samples 6 van Wering ER, van der Linden-Schrever BE, van der Velden VHJ, taken during induction therapy and are present at low Szczepanski T, van Dongen JJM. T- in bone marrow frequencies during other stages of therapy.6 In fact, the samples of children with acute lymphoblastic leukemia during and after chemotherapy might hamper PCR-based minimal residual percentage of T cells in PB buffy coats obtained from healthy disease studies. Leukemia 2001; 15: 1301–1303. individuals will be significantly higher than in most bone 7 van Dongen JJM, Seriu T, Panzer-Grumayer ER, Biondi A, Pongers- marrow samples. Consequently, the NSA of TCRG gene Willemse MJ, Corral L et al. Prognostic value of minimal residual rearrangements observed in bone marrow samples generally is disease in acute lymphoblastic leukaemia in childhood. Lancet lower than that observed in normal PB buffy coat DNA and 1998; 352: 1731–1738. limited variations in the number of T cells present in bone 8 van Zelm MC, van der Burg M, de Ridder D, Barendregt BH, de Haas EF, Reinders MJ et al. Ig gene rearrangement steps are marrow will not have any impact on RQ-PCR data interpreta- initiated in early human precursor B cell subsets and correlate with tion. Since the NSA for TCRG will be higher in PB buffy coat (as specific transcription factor expression. J Immunol 2005; 175: generally used for defining the Quantitative Range) than in bone 5912–5922.

A novel cytogenetic aberration found in stem cell leukemia/ syndrome

Leukemia (2008) 22, 644–646; doi:10.1038/sj.leu.2404942; myeloid leukemia (AML) and cytogenetic abnormalities invol- published online 11 October 2007 ving 8p11.1,2 We report a patient who demonstrated similar clinical features accompanied by a novel translocation. The stem cell leukemia/lymphoma syndrome is characterized by A 47-year-old male presented with lymphadenopathy and concurrent lymphoma, myeloid proliferation evolving to acute splenomegaly in August 2006. A lymph node biopsy established

Leukemia Letters to the Editor 645

Figure 1 Stem cell leukemia/lymphoma syndrome: lymph node and bone marrow biopsy, and the novel t(8;12)(q11;p12) translocation. (a) Cervical lymph node biopsy showing lymphoblast infiltrate (hematoxylin and eosin stain, Â 400). (b and c) Trephine bone biopsy: leukemic infiltrate, eosinophilia and prominent increase in reticulin fibers. (d) Karyotype of Q-banded metaphase from bone marrow aspirate showing t(8;12)(q11;p12) translocation.

the diagnosis of T-lymphoblastic lymphoma along with promi- Should we perform allogeneic stem cell transplantation as the nent eosinophilia (Figure 1a). The lymphoblasts expressed initial therapeutic program? Or does he have T-lymphoblastic terminal deoxynucleotidyl transferase and CD1a, CD2, CD5 lymphoma with eosinophilia, a curable disease? Currently, 60% antigens. A bone marrow biopsy revealed severe myeloid of these patients are cured with chemotherapy protocols for ALL.3 hyperplasia with eosinophilia, increased reticulin fibers and no Moreover, the expression of CD1a representing a stage of cortical evidence of lymphoma involvement. Cytogenetic analysis showed thymic differentiation is associated with a favorable outcome a 46,XY,t(8;12)(q11;p12) karyotype in all of 15 mitoses analyzed in ALL.4 We started with intensive chemotherapy and search for (Figure 1d). Polymerase chain reactions displayed rearrangement an human leukocyte antigen-compatible donor for stem cell of T-cell receptor TCR-g and were negative for the bcr-abl transplantation, which was performed soon after transformation translocation, JAK-2 mutation and FIP1L1/PDGFRA fusion gene. to AML. Unfortunately, the leukemia developed promptly, was Chemotherapy according to the GMALL protocol resulted in resistant to myeloablative chemotherapy and caused death. disappearance of clinical symptoms. Nevertheless, repeated In conclusion, our case demonstrates that stem cell leukemia/ bone marrow examination demonstrated persistent myelofibro- lymphoma syndrome is not restricted only to previously sis and the same cytogenetic aberration. Methotrexate and described 8p11 and may be associated with other genetic cytarabine were administered at high doses. In December 2006, alterations, such as t(8;12)(q11;p12), found in our case. This leukocytosis 30 Â 109 per litre with 20% blastosis occurred. The syndrome with a different chromosomal abnormality bears also circulating blasts showed myelomonocytic morphology, stained a bad prognosis due to rapid development of resistant leukemia. for myeloperoxidase and expressed CD33 and CD13 antigens. 1 1 1 2 3 The bone marrow findings were consistent with the diagnosis of L Shvidel , E Sigler , E Vorst , E Feldberg , N Voskoboinic , M Shtalrid1 and A Berrebi1 AML with fibrosis (Figure 1b and c). The patient underwent stem 1 cell transplantation from a HLA-matched unrelated donor, but Hematology Institute, Kaplan Medical Center, Rehovot, Israel; he died with overt leukemia and sepsis shortly afterwards. 2Pathology Department, Kaplan Medical Center, We present a patient with the clinical features of the rare stem Rehovot, Israel and cell leukemia/lymphoma syndrome described so far in association 3Cytogenetics Laboratory, Kaplan Medical Center, Rehovot, 1,2 with 8p11 abnormalities. This syndrome usually presents as Isreal; T-cell lymphoblastic lymphoma accompanied by myeloid hyper- Affiliated to the School of Medicine, Hebrew University plasia. The disorder generally progresses to full-blown AML within and Hadassah, Jerusalem, Israel a year from diagnosis and bears bad prognosis, although there is a E-mail: [email protected] potential for cure with allogeneic stem cell transplantation.2 Our patient demonstrated a new chromosomal aberration References t(8;12)(q11;p12). The short arm of chromosome 12 is frequently translocated in different hematological malignancies; however, it is not yet known as a partner for 8q11. 1 Inhorn RC, Aster JC, Roach SA, Slapak CA, Soiffer R, Tantravahi R et al. A syndrome of lymphoblastic lymphoma, eosinophilia, and At presentation, our patient disclosed diagnostic and therapeu- myeloid hyperplasia/malignancy associated with t(8;13)(p11;q11): tic problems. Does he have a fatal disease similar to 8p11 description of a distinctive clinicopathologic entity. Blood 1995; 85: syndrome? Should we treat him aggressively with AML protocols? 1881–1887.

Leukemia Letters to the Editor 646 2 Macdonald D, Reiter D, Cross NC. The 8p11 myeloproliferative according to protocols for acute lymphoblastic leukemia. Blood syndrome: a distinct clinical entity caused by constitutive activation 2002; 99: 4379–4385. of FGFR1. Acta Haematol 2002; 107: 101–107. 4 Pui CH, Behm FG, Crist WM. Clinical and biologic relevance of 3 Hoelzer D, Gokbuget N, Digel W, Faak T, Kneba M, Reutzel R et al. immunologic marker studies in childhood acute lymphoblastic Outcome of adult patients with T-lymphoblastic lymphoma treated leukemia. Blood 1993; 82: 343–362.

Pulmonary arterial hypertension in primary myelofibrosis is common and associated with an altered angiogenic status

Leukemia (2008) 22, 646–649; doi:10.1038/sj.leu.2404943; endothelial cells (CECs, defined as CD45À, CD31 þ and published online 13 September 2007 P1H12 þ ) and CD34 þ cells (defined as CD45 þ and CD34 þ ) were quantified by flow cytometry. Serum concentrations of VEGF, endothelin-1 (ET-1), TGFb, PDGF AB and E-selectin were Angiogenesis plays an important role in the pathogenesis of assessed by means of commercial enzyme-linked immunosor- both pulmonary arterial hypertension (PAH) and chronic myelo- bent assays. Bone marrow microvessel density (MVD) was proliferative disorders (CMPDs).1,2 The WHO classification of evaluated using the ‘hot spots’ method on 33 biopsy specimens pulmonary hypertension includes CMPDs as diseases associated of the PMF patients, and compared with the figures obtained in with PAH development1 and, according to the literature, 16 healthy controls. pulmonary hypertension affects between 13 and 48% of patients Endothelial progenitor cells are mobilizable bone marrow- with myeloproliferative diseases. It has been suggested that this derived stem cells that can home into sites of active angiogen- comorbidity has a multifactorial pathobiological origin, including esis. However, the magnitude and physiological importance of the presence of pulmonary myeloid metaplasia, the obstruction of this property is currently debated. Other lines of evidence also pulmonary vessels by circulating megakaryocytes, smooth muscle show that a large number of EPCs with enhanced functionality hyperplasia due to platelet-derived growth factor (PDGF), and may have protective properties against endothelium-dependent thromboembolic events.3,4 However, little is known about the diseases such as coronary artery diseases.6 In addition, it has origin of the association, and the possible pathogenetic link recently been reported that the number of circulating EPCs is between CMPDs and PAH has not yet been studied. increased in PMF, and this was suggested as being associated We investigated this association in primary myelofibrosis with its pro-angiogenic phenotype.7 (PMF) diagnosed on the basis of the WHO classification.5 The The median number of EPCs in the controls and S-PH patients study group consisted of 36 patients being followed up at our was similarly low (0.29 Â 106 lÀ1 (0.13–1.71) and 0.41 Â 106 lÀ1 institution: 22 with PMF, 7 with PMF developing from (0–0.56)), but it was significantly higher in the PMF patients polycythemia vera and 7 with PMF progressing from essential (0.77 Â 106 lÀ1 (0–4.31); P ¼ 0.02 vs controls; P ¼ 0.01 vs S-PH; thrombocythemia. Their clinical characteristics are summarized Figure 1b). The PMF patients without PAH had more EPCs than in Table 1. The control groups consisted of 10 healthy subjects those with sPAPX35 mm Hg (0.94 Â 106 lÀ1 (0.13–4.31) vs (controls) and 10 patients with pulmonary hypertension due to 0.43 Â 106 lÀ1 (0–2.46); P ¼ 0.009; Figure 1c), and there was a other causes (S-PH). negative correlation between the EPC counts and sPAP levels The Mann–Whitney U test was used for between-group comparisons, and Spearman’s correlation coefficient was computed to evaluate the associations between variables. Table 1 Clinical characteristics of the 36 PMF patients (pts) Systolic pulmonary artery pressure (sPAP) was evaluated in all patients by means of color Doppler echocardiography and PAH Median value or absolute number was defined as an sPAPX35 mm Hg. Secondary causes of sPAP (range or percentage) elevation were excluded by means of echocardiography, high- Age (years) 64.5 (36–83) resolution lung CT scan, arterial blood gas evaluations, Male/female 20/16 pts pulmonary function tests with CO diffusion and lung perfusion Hb (g dlÀ1) 11.8 (9–16.2) scintigraphy. PAH was found in 13 patients (36%), 6 of whom WBC ( Â 106 lÀ1) 8.95 (2.7–35.5) 6 À1 had moderate pulmonary hypertension (sPAP 45–55 mm Hg); in Plt ( Â 10 g ) 470 (135–1414) Spleen diameter (cm in 16 (10–26) none of the cases, the sPAP elevation was due to cardiopul- echography) monary or thromboembolic diseases: the median pO2 was JAK2V617F mutation 20 pts (56%) 88 mm Hg (range: 82–96) and the SO2 97% (range: 96–99), and Dupriez score 0 ¼ 29 pts, 1 ¼ 3 pts, 2 ¼ 4 pts the other examinations provided no relevant results. Time from diagnosis to 39 (8–248) Three patients with PAH-related PMF complained of symp- evaluation (months) a a toms attributable to PAH, such as dyspnea on exertion or Histology PMF-0 ¼ 9 pts, PMF-1 ¼ 13 pts, PMF-2a 12 pts, PMF-3a 2 pts fatigue. They had slightly lower median hemoglobin levels than ¼ ¼ À1 Transfusion dependence 5 pts (14%) the PMF patients as a whole (10.1 vs 11.8 g dl , P ¼ NS). The Chemotherapy 14 pts: hydroxyurea, 2 pts: busulfan presence of PAH did not correlate with disease duration or any Antiplatelet therapy 19 pts (53%) of the clinical features listed in Table 1. History of thrombosis 6 pts (17%) In addition to the above clinical analysis, we also evaluated Abbreviation: Hb, hemoglobin; Plt, platelet; PMF, primary myelofibro- laboratory parameters related to angiogenesis and PAH devel- sis; WBC, . opment. Peripheral blood levels of endothelial progenitor cells aChronic idiopathic myelofibrosis (CIMF)-0, -1, -2 and -3 according to (EPCs, defined as CD45À, CD34 þ and CD133 þ ), circulating the WHO classification.

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