Predictive Value of miR-146a rs2431697 Polymorphism to Myelofibrosis Progression in Patients with Myeloproliferative Neoplasm.

BACKGROUND: Bone marrow myelofibrosis (BMF) that develop on top of Polycythaemia vera (PV) and essential thrombocythemia leads to shortening of the patient's overall survival. This study aimed to address the impact of miR-146a rs2431697 polymorphism on inflammatory biomarkers and genes expression and the hazards of myelofibrosis progression. PATIENTS AND METHODS: The study included 88 myeloproliferative neoplasm (40 PV; 27 ET; 21 MF) and 90 healthy controls. For all investigated subjects miR-146a rs2431697 genotypes were identified by sequencing and the expression of miR-146a; IL-1ß; NF-κB; a NOD-like receptor family, pyrin domain containing 3 (NLRP3) (NLRP3) genes were estimated by real time PCR. RESULTS: miR146a genotypes revealed that there was significant association between TT and TC genotypes with MF. The degree of miR146a expression was significantly reduced in MF as compared to both PV and ET. In contrast; the levels of IL-1ß; NF-κB; NLRP3 genes expression were significantly elevated in MF patients group as compared to PV and ET patients' group. Multivariate analysis identified TT genotype as poor predictor of MF progression. CONCLUSION: miR-146a rs2431697 TT genotype is associated with high risk of MF progression in MPN patients. Targeting of IL-1ß; NF-κB; NLRP3 genes might help  in hindering of  MF progression in  MPN patients,
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Bone marrow mammaglobin-1 (SCGB2A2) immunohistochemistry expression as a breast cancer specific marker for early detection of bone marrow micrometastases.

Despite all the advances in the management of breast cancer (BC), patients with distance metastasis are still considered incurable with poor prognosis. For that reason, early detection of the metastatic lesions is crucial to improve patients' life span as well as quality of life. Many markers were proposed to be used as biomarkers for metastatic BC lesions, however many of them lack organ specificity. This highlights the need for novel markers that are more specific in detecting disseminated BC lesions. Here, we investigated mammaglobin-1 expression as a potential and specific marker for metastatic BC lesions using our patient cohort consisting of 30 newly diagnosed BC patients. For all patients, bone marrow (BM) aspiration, BM biopsy stained by H&E and BM immunohistochemically stained for mammaglobin-1 were performed. In addition, the CA15-3 in both serum and bone marrow plasma was also evaluated for each patient. Indeed, mammaglobin-1 immuno-staining was able to detect BM micrometastases in 16/30 patients (53.3%) compared to only 5/30 patients (16.7%) in BM biopsy stained by H&E and no cases detected by BM aspirate (0%). In addition, our results showed a trend of association between mammaglobin-1 immunoreactivity and the serum and BM plasma CA15-3. Further validation was done using large publicly available databases. Our results showed that mammaglobin-1 gene expression to be specifically upregulated in BC patients' samples compared to normal tissue as well as samples from other cancers. Moreover, our findings also showed mammaglobin-1 expression to be a marker of tumour progression presented as lymph nodes involvement and distant metastasis. These results provide an initial evidence for the use of mammaglobin-1 (SCGB2A2) immunostaining in bone marrow as a tool to investigate early BM micrometastases in breast cancer.

Clinical features and treatment of patients with lung adenocarcinoma with bone marrow metastasis.

BACKGROUND: Bone marrow metastasis occurs in lung adenocarcinoma patients with a poor prognosis due to the late course and lack of definitive treatments, although reports on this are limited. This study analyzed the clinical manifestation, laboratory examination, treatment, and prognosis of patients with lung adenocarcinoma with bone marrow metastasis. METHODS: All patients were confirmed to have bone marrow infiltration by bone marrow aspiration. The clinical data of 12 patients with lung adenocarcinoma with bone marrow metastasis were analyzed retrospectively. The prognostic factors were analyzed by Kaplan-Meier statistics. RESULTS: The common biomarker abnormalities in 12 patients were elevated carcinoembryonic antigen in 12 cases (100%), elevated lactate dehydrogenase in 9 cases (75%), increased alkaline phosphatase and anemia in 8 cases each (66.7%), and thrombocytopenia in 4 cases (33.3%). After diagnosis of bone marrow metastasis, 5 patients were treated with platinum-based chemotherapy, 3 patients received chemotherapy and targeted drug tyrosine kinase inhibitor (TKI) therapy, 2 patients received simple TKI therapy, and 2 patients received only best supportive care (BSC) therapy. The median duration of survival after the diagnosis of bone marrow involvement was 422 days. The survival time of patients receiving TKI therapy after bone marrow metastasis was significantly better than that of patients receiving only BSC and chemotherapy (χ2=4.636, P=0.031). CONCLUSIONS: The survival period of patients with lung adenocarcinoma with bone marrow metastasis is short, and targeted drug TKI treatment can prolong the survival time for patients with EGFR mutation-carrying lung adenocarcinoma with bone marrow metastasis.

Concurrent JAK2-Positive Myeloproliferative Disorder and Chronic Myelogenous Leukemia: A Novel Entity? A Case Report With Review of the Literature.

JAK2 V617F mutation and BCR-ABL translocation have been considered to be mutually exclusive. However, many cases where both hits coexisted have been reported. We have personally managed a case too. We believe this hybrid entity is underdiagnosed. Thus, we decided to shed light on this "double hit" disease to improve its diagnosis and optimize its treatment. We reviewed the English literature in PubMed since JAK2 discovery. We found 33 cases reported so far. We summarized patient characteristics and analyzed possible interactions between JAK2 and BCR-ABL clones.

Myeloproliferative neoplasms with concurrent BCR-ABL1 translocation and JAK2 V617F mutation: a multi-institutional study from the bone marrow pathology group.

Myeloproliferative neoplasms arise from hematopoietic stem cells with somatically altered tyrosine kinase signaling. Classification of myeloproliferative neoplasms is based on hematologic, histopathologic and molecular characteristics including the presence of the BCR-ABL1 and JAK2 V617F. Although thought to be mutually exclusive, a number of cases with co-occurring BCR-ABL1 and JAK2 V617F have been identified. To characterize the clinicopathologic features of myeloproliferative neoplasms with concomitant BCR-ABL1 and JAK2 V617F, and define the frequency of co-occurrence, we conducted a retrospective multi-institutional study. Cases were identified using a search of electronic databases over a decade at six major institutions. Of 1570 patients who were tested for both BCR-ABL1 and JAK2 V617F, six were positive for both. An additional five patients were identified via clinical records providing a total of 11 cases for detailed evaluation. For each case, clinical variables, hematologic and genetic data, and bone marrow histomorphologic features were analyzed. The sequence of identification of the genetic abnormalities varied: five patients were initially diagnosed with a JAK2 V617F+ myeloproliferative neoplasm, one patient initially had BCR-ABL1+ chronic myeloid leukemia, while both alterations were identified simultaneously in five patients. Classification of the BCR-ABL1-negative myeloproliferative neoplasms varied, and in some cases, features only became apparent following tyrosine kinase inhibitor therapy. Seven of the 11 patients showed myelofibrosis, in some cases before identification of the second genetic alteration. Our data, reflecting the largest reported study comprehensively detailing clinicopathologic features and response to therapy, show that the co-occurrence of BCR-ABL1 and JAK2 V617F is rare, with an estimated frequency of 0.4%, and most often reflects two distinct ('composite') myeloproliferative neoplasms. Although uncommon, it is important to be aware of this potentially confounding genetic combination, lest these features be misinterpreted to reflect resistance to therapy or disease progression, considerations that could lead to inappropriate management.

Neuroblastoma cells undergo transcriptomic alterations upon dissemination into the bone marrow and subsequent tumor progression.

Neuroblastoma is the most common extracranial solid tumor in childhood. The vast majority of metastatic (M) stage patients present with disseminated tumor cells (DTCs) in the bone marrow (BM) at diagnosis and relapse. Although these cells represent a major obstacle in the treatment of neuroblastoma patients, insights into their expression profile remained elusive. The present RNA-Seq study of stage 4/M primary tumors, enriched BM-derived diagnostic and relapse DTCs, as well as the corresponding BM-derived mononuclear cells (MNCs) from 53 patients revealed 322 differentially expressed genes in DTCs as compared to the tumors (q < 0.001, |log2 FC|>2). Particularly, the levels of transcripts encoded by mitochondrial DNA were elevated in DTCs, whereas, for example, genes involved in angiogenesis were downregulated. Furthermore, 224 genes were highly expressed in DTCs and only slightly, if at all, in MNCs (q < 8 × 10-75 log2 FC > 6). Interestingly, we found the transcriptome of relapse DTCs largely resembling those of diagnostic DTCs with only 113 differentially expressed genes under relaxed cut-offs (q < 0.01, |log2 FC|>0.5). Notably, relapse DTCs showed a positional enrichment of 31 downregulated genes on chromosome 19, including five tumor suppressor genes: SIRT6, BBC3/PUMA, STK11, CADM4 and GLTSCR2. This first RNA-Seq analysis of neuroblastoma DTCs revealed their unique expression profile in comparison to the tumors and MNCs, and less pronounced differences between diagnostic and relapse DTCs. The latter preferentially affected downregulation of genes encoded by chromosome 19. As these alterations might be associated with treatment failure and disease relapse, further functional studies on DTCs should be considered.

The Mutational Landscape of Circulating Tumor Cells in Multiple Myeloma.

The development of sensitive and non-invasive "liquid biopsies" presents new opportunities for longitudinal monitoring of tumor dissemination and clonal evolution. The number of circulating tumor cells (CTCs) is prognostic in multiple myeloma (MM), but there is little information on their genetic features. Here, we have analyzed the genomic landscape of CTCs from 29 MM patients, including eight cases with matched/paired bone marrow (BM) tumor cells. Our results show that 100% of clonal mutations in patient BM were detected in CTCs and that 99% of clonal mutations in CTCs were present in BM MM. These include typical driver mutations in MM such as in KRAS, NRAS, or BRAF. These data suggest that BM and CTC samples have similar clonal structures, as discordances between the two were restricted to subclonal mutations. Accordingly, our results pave the way for potentially less invasive mutation screening of MM patients through characterization of CTCs.

The spleen microenvironment influences disease transformation in a mouse model of KITD816V-dependent myeloproliferative neoplasm.

Activating mutations leading to ligand-independent signaling of the stem cell factor receptor KIT are associated with several hematopoietic malignancies. One of the most common alterations is the D816V mutation. In this study, we characterized mice, which conditionally express the humanized KITD816V receptor in the adult hematopoietic system to determine the pathological consequences of unrestrained KIT signaling during blood cell development. We found that KITD816V mutant animals acquired a myeloproliferative neoplasm similar to polycythemia vera, marked by a massive increase in red blood cells and severe splenomegaly caused by excessive extramedullary erythropoiesis. Moreover, we found mobilization of stem cells from bone marrow to the spleen. Splenectomy prior to KITD816V induction prevented expansion of red blood cells, but rapidly lead to a state of aplastic anemia and bone marrow fibrosis, reminiscent of post polycythemic myeloid metaplasia, the spent phase of polycythemia vera. Our results show that the extramedullary hematopoietic niche microenvironment significantly influences disease outcome in KITD816V mutant mice, turning this model a valuable tool for studying the interplay between functionally abnormal hematopoietic cells and their microenvironment during development of polycythemia vera-like disease and myelofibrosis.

Focal nodular and diffuse haematopoietic marrow hyperplasia in patients with underlying malignancies: a radiological mimic of malignancy in need of recognition.

AIM: To report the authors' experience of focal nodular haematopoietic marrow hyperplasia (FNHMH) and diffuse haematopoietic marrow hyperplasia (DHMH) clinically masquerading as skip, distant, or disseminated metastasis in seven patients with underlying malignant neoplasms. MATERIALS AND METHODS: Five patients with FNHMH and two with DHMH mistaken radiologically as skip and disseminated metastasis, respectively, were compared and contrasted with four patients with osteosarcomas and two with chondrosarcomas harbouring skip metastasis, noting the temporal relationship with their haematological profile. RESULTS: FNHMH and DHMH were undetectable by plain radiography and computed tomography (CT) except one showing subtle sclerosis on CT. They showed either isointense or hyperintense, but not hypointense, attenuation at T1-weighted imaging, and all showed hyperintense attenuation at T2-weighted MRI relative to skeletal muscle. Of the five patients who underwent bone scintigraphy, one showed mildly increased uptake, and one out of two showed markedly increased 2-[18F]-fluoro-2-deoxy-d-glucose (FDG)-positron-emission tomography (PET) uptake. The rates for sarcoma skip metastasis by plain radiography, CT, MRI, and bone scintigraphy were 40%, 66.7%, 100%, and 66.7%, respectively. At MRI, 60% showed hypointense and 40% isointense attenuation at T1-weighted, 80% hyperintense and 20% hypointense attenuation at T2-weighted imaging. Combined FDG-PET and CT, which was performed in only one patient, failed to show the skip metastasis. Not every patient with FNHMH or DHMH received granulocyte colony-stimulating factor (GCSF), but all had low or falling haemoglobin levels, which may thus be the prime cause for HMH. CONCLUSIONS: Due to overlapping radiological features, FNHMH and DHMH are great radiological mimics of malignancy. In some cases, needle biopsy is required for their definitive differentiation.

Inconspicuous Presentation of Metastatic Neuroblastoma.

Neuroblastoma is a malignant tumor arising from nerve tissue that accounts for approximately 15 percent of pediatric cancer fatalities. Primary tumors most commonly arise in sympathetic nervous tissue of the abdomen and metastasize to the bone marrow, liver, and lymph nodes. This case report depicts a 3-year-old girl who presented with a recurring fever, runny nose, and a positive test for rhinovirus suggesting a simple case of the common cold. Further investigation, however, revealed stage 4 neuroblastoma. This patient experience emphasizes the importance of having a high level of suspicion to rule out more serious underlying pathology in a seemingly unremarkable patient presentation.

Comparison between Use of PSA Kinetics and Bone Marrow Micrometastasis to Define Local or Systemic Relapse in Men with Biochemical Failure after Radical Prostatectomy for Prostate Cancer.

BACKGROUND: Treatment of biochemical failure after radical prostatectomy for prostate cancer is largely empirically based. The use of PSA kinetics has been used as a guide to determine local or systemic treatment of biochemical failure. We here compared PSA kinetics with detection of bone marrow micrometastasis as methods to determine local or systemic relapse. MATERIALS AND METHODS: A transversal study was conducted of men with biochemical failure, defined as a serum PSA >0.2ng/ml after radical prostatectomy. Consecutive patients having undergone radical prostatectomy and with biochemical failure were enrolled and clinical and pathological details were recorded. Bone marrow biopsies were obtained from the iliac crest and touch prints made, micrometastasis (mM) being detected using anti-PSA. The clinical parameters of total serum PSA, PSA velocity, PSA doubling time and time to biochemical failure, age, Gleason score and pathological stage were registered. RESULTS: A total of 147 men, mean age 71.6 ± 8.2 years, with a median time to biochemical failure of 5.5 years (IQR 1.0-6.3 years) participated in the study. Bone marrow samples were positive for micrometastasis in 98/147 (67%) of patients at the time of biochemical failure. The results of bone marrow micrometastasis detected by immunocytochemistry were not concordant with local relapse as defined by PSA velocity, time to biochemical failure or Gleason score. In men with a PSA doubling time of < six months or a total serum PSA of >2,5ng/ml at the time of biochemical failure the detection of bone marrow micrometastasis was significantly higher. CONCLUSIONS: The detection of bone marrow micrometastasis could be useful in defining systemic relapse, this minimally invasive procedure warranting further studies with a larger group of patients.

Paraneoplastic granulocyte colony-stimulating factor secretion in soft tissue sarcoma mimicking myeloproliferative neoplasia: a case report.

BACKGROUND: While paraneoplastic leukocytosis is a common phenomenon in solid tumors, extreme elevations of white blood counts (WBC) in the range of more than 100,000/µl are uncommon in patients with non-hematologic malignancies. Leukocytosis with mature neutrophils due to a granulocyte colony-stimulating factor (G-CSF) producing tumor is only seen on rare occasions. CASE PRESENTATION: Massive neutrophil leukocytosis of approximately 100,000/µl was diagnosed in a 57-year-old Caucasian woman with metastatic undifferentiated endometrial sarcoma. A bone marrow trephine biopsy revealed massively increased granulopoiesis, but no evidence of monoclonal myeloproliferative disease. After the primary tumor had been resected, white blood count (WBC) plummeted and went back to nearly normal levels within one week. With progressive metastatic disease, granulocyte colony-stimulating factor (G-CSF) plasma levels were found to be increased by 10-fold. White blood count (WBC) strictly correlated with tumor burden and response to chemotherapy. In the final stage of treatment resistent disease, white blood count (WBC) approximated 300,000/µl. CONCLUSION: We report on a granulocyte colony-stimulating factor (G-CSF) secreting undifferentiated endometrial sarcoma, which was associated with extreme neutrophil counts. White blood count (WBC) were closely correlated with tumor burden and associated with an aggressive clinical course. We suggest that paraneoplastic neutrophilia represents a poor prognostic sign in soft tissue sarcoma. In patients with similar constellations, antitumor therapy must not be delayed.

Loss of Stat1 decreases megakaryopoiesis and favors erythropoiesis in a JAK2-V617F-driven mouse model of MPNs.

The interferon-γ (IFNγ)/signal transducer and activator of transcription 1 (Stat1) pathway shows higher activity in patients with essential thrombocythemia (ET) than in polycythemia vera (PV) and was proposed to be promoting the ET phenotype. We explored the phenotypic consequences of Stat1 deficiency on the effects of Janus kinase 2 (JAK2)-V617F in vivo by crossing mice expressing JAK2-V617F with Stat1 knockout mice. JAK2-V617F;Stat1(-/-) double transgenic mice showed higher red cell parameters and lower platelet counts compared with JAK2-V617F;Stat1(+/+) mice. Bone marrow transplantation reproduced these phenotypic changes in wild-type recipients, demonstrating that the effect of Stat1 is cell-intrinsic and does not require a Stat1-deficient microenvironment. Deletion of Stat1 increased burst-forming unit-erythroid and reduced colony-forming unit-megakaryocyte colony formation driven by JAK2-V617F, but was not sufficient to completely normalize the platelet count. Gata1, a key regulator of megakaryopoiesis and erythropoiesis, was decreased in Stat1-deficient platelets. V617F transgenic mice with thrombocytosis had higher serum levels of IFNγ than normal controls and patients with ET showed higher IFNγ serum levels than patients with PV. Together, these results support the concept that activating Stat1 in the presence of JAK2-V617F, for example, through IFNγ, constrains erythroid differentiation and promotes megakaryocytic development, resulting in ET phenotype.

Prognostic factors in adult patients with solid cancers and bone marrow metastases.

BACKGROUND: Solid cancers with bone marrow metastases are rare but lethal. This study aimed to identify clinical factors predictive of survival in adult patients with solid cancers and bone marrow metastases. METHODS: A total of 83 patients were enrolled consecutively between January 1, 2000 and December 31, 2012. Bone marrow metastases were confirmed by biopsies. Patient clinical features and laboratory data were analyzed for associations. RESULTS: The median age of the patients was 54 years (range, 23-88 years), and 58% were male. The 3 most common primary tumor locations were the stomach (32 patients, 39%), prostate (16 patients, 19%), and lungs (12 patients, 15%). The median overall survival was 49 days (range, 3-1423 days). Patients with Eastern Cooperative Oncology Group performance status 1, cancers of prostate origin, platelet counts over 50,000/ml, and undergoing antitumor therapies had a significantly better prognosis in the multivariate analysis. The median survival times were 173 and 33 days for patients with 2-3 more favorable parameters (n=24) and those with 0-1 (n=69), respectively (hazard ratio 0.30; 95% CI 0.17-0.52, p<0.001). CONCLUSIONS: Solid cancers with bone marrow metastases are dismal and incurable diseases. Understanding prognostic factors to these diseases helps medical personnel to provide appropriate treatments and better inform patients about outcomes. Antitumor therapies may improve outcomes in selected patient cohorts.

Global coagulation in myeloproliferative neoplasms.

In spite of their recognized risk of thrombosis, patients with myeloproliferative neoplasms (MPN) show little or no abnormalities of traditional coagulation tests, perhaps because these are unable to represent the balance between pro- and anticoagulants nor the effect of platelets and blood cells. We investigated whether global tests such as thrombin generation in platelet-rich plasma (PRP) or thromboelastometry in whole blood were able to detect signs of procoagulant imbalance in MPN. The endogenous thrombin potential (ETP) of 111 patients and 89 controls was measured in PRP with platelet count adjusted to the original patient- or control-count. Testing was performed with and without thrombomodulin (the physiological protein C activator) and results were expressed as ETP ratios (with/without thrombomodulin). High ETP ratios reflect resistance to thrombomodulin and were taken as indexes of procoagulant imbalance. Patients were also investigated by thromboelastometry that provides such parameters as the clot formation time (CFT) and maximal clot firmness (MCF). Short CFT or high MCF were taken as indexes of procoagulant imbalance. ETP ratios were higher in patients than in controls and were directly correlated with platelet counts and inversely with the plasma levels of free protein S, protein C and antithrombin. Patients on hydroxyurea had lower ETP ratios than those on other treatments. CFT was shorter and MCF was greater in patients than controls; CFT and MCF were correlated with platelet counts. In conclusion, patients with MPN display a procoagulant imbalance detectable by thrombin generation and thromboelastometry. These tests might be useful in the frame of clinical trials to assess their association with the occurrence of thrombosis and with the effect of therapeutic strategies in MPN.

Megakaryocytes, malignancy and bone marrow vascular niches.

Dynamic interactions between hematopoietic cells and their specialized bone marrow microenvironments, namely the vascular and osteoblastic 'niches', regulate hematopoiesis. The vascular niche is conducive for thrombopoiesis and megakaryocytes may, in turn, regulate the vascular niche, especially in supporting vascular and hematopoietic regeneration following irradiation or chemotherapy. A role for platelets in tumor growth and metastasis is well established and, more recently, the vascular niche has also been implicated as an area for preferential homing and engraftment of malignant cells. This article aims to provide an overview of the dynamic interactions between cellular and molecular components of the bone marrow vascular niche and the potential role of megakaryocytes in bone marrow malignancy.

JAK2 V617F-dependent upregulation of PU.1 expression in the peripheral blood of myeloproliferative neoplasm patients.

Myeloproliferative neoplasms (MPN) are multiple disease entities characterized by clonal expansion of one or more of the myeloid lineages (i.e. granulocytic, erythroid, megakaryocytic and mast cell). JAK2 mutations, such as the common V617F substitution and the less common exon 12 mutations, are frequently detected in such tumor cells and have been incorporated into the diagnostic criteria published by the World Health Organization since 2008. However, the mechanism by which these mutations contribute to MPN development is poorly understood. We examined gene expression profiles of MPN patients focusing on genes in the JAK-STAT signaling pathway using low-density real-time PCR arrays. We identified the following 2 upregulated genes in MPN patients: a known target of the JAK-STAT axis, SOCS3, and a potentially novel target, SPI1, encoding PU.1. Induction of PU.1 expression by JAK2 V617F in JAK2-wildtype K562 cells and its downregulation by JAK2 siRNA transfection in JAK2 V617F-positive HEL cells supported this possibility. We also found that the ABL1 kinase inhibitor imatinib was very effective in suppressing PU.1 expression in BCR-ABL1-positive K562 cells but not in HEL cells. This suggests that PU.1 expression is regulated by both JAK2 and ABL1. The contribution of the two kinases in driving PU.1 expression was dominant for JAK2 and ABL1 in HEL and K562 cells, respectively. Therefore, PU.1 may be a common transcription factor upregulated in MPN. PU.1 is a transcription factor required for myeloid differentiation and is implicated in erythroid leukemia. Therefore, expression of PU.1 downstream of activated JAK2 may explain why JAK2 mutations are frequently observed in MPN patients.

Blastic plasmacytoid dendritic cell neoplasm expressing the CD13 myeloid antigen.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN), currently considered to originate from immature plasmacytoid dendritic cells (DC), is a rare and aggressive CD4+CD56+ neoplasm that frequently involves the skin and bone marrow. We present a case of an 80-year-old man with a CD4+CD56+ BPDCN that affected the orbital cavity and bone marrow. Although BPDCN has not been reported to express any lineage-specific markers, the neoplastic cells strongly expressed the CD13 antigen. Therefore, in addition to pathological examination, we attempted to induce in vitro morphological and surface marker changes with IL-3 and CD40 ligand. After treatment with these cytokines, the tumor cells enlarged markedly, acquired many fine dendrites, similar to mature DC, and showed enhanced expression of antigens specific to DC or antigen-presenting cells, such as CD40, CD80, CD83 and CD86. To the best of our knowledge, this is the first report of BPDCN expressing a myeloid antigen, CD13, although CD33 expression has been described in some cases. The present patient received 2 courses of combination chemotherapy consisting of cytarabine and etoposide, which resulted in complete remission. Given that the cellular origin of plasmacytoid DC is still controversial, myeloid antigen expression involving CD13 may not exclude a diagnosis of BPDCN.