Bilineage T lymphoid and myeloid (T/My) neoplasms are rare entities among the hematopoietic and lymphoid malignancies. The majority of patients present with leukemic symptoms in which blasts are observed in the peripheral blood (PB) or bone marrow (BM) at a percentage of >20% of nucleated cells. Only a minimal number of cases of T/My bilineage hematopoietic and lymphoid malignancy have been reported with extramedullary infiltration as the initial symptom. The origin of the neoplastic cells in T/My bilineage malignancy has been documented as the hematopoietic stem cells. The present study reports the case of a 31-year-old man with a T/My bilineage malignancy, which initially showed cervical lymph node enlargement beyond the diagnostic criteria of leukemia in the PB and in the BM. Two distinct malignant populations were detected in the cervical lymph node and pleural effusion, one of which was positive for MPO-staining, while the other was positive for cytoplasmic cluster of differentiation 3. Mutations in platelet-derived growth factor receptor α, platelet-derived growth factor receptor β, fibroblast growth factor receptor 1 and other chromosome abnormalities were excluded. The patient obtained complete remission after conventional chemotherapy, but relapsed with bilineage leukemia within a short period of time. Lymphoid and myeloid lineages have been reported to be differentiated from multipotent progenitors asymmetrically. However, the cellular mutation stage in T/My bilineage malignancy remains unclear. The present study also reviews the origin, development and therapeutic strategies for extramedullary T/My bilineage malignancy.

Vandetanib is an orally active small molecule tyrosine kinase inhibitor (TKI) with activity against several pathways implicated in malignancy including the vascular endothelial growth factor receptor pathway, the epidermal growth factor receptor pathway, the platelet derived growth factor receptor β pathway, and REarranged during Transfection pathway. To determine if vandetanib-mediated inhibition of receptor tyrosine kinases is a potential therapeutic strategy for pediatric acute leukemia, these studies aimed to characterize the activity of vandetanib against acute leukemia in vitro. Treatment of leukemia cell lines with vandetanib resulted in a dose-dependent decrease in proliferation and survival. Vandetanib's anti-leukemic activity appeared mediated by multiple mechanisms including accumulation in G1 phase at lower concentrations and apoptosis at higher concentrations. Alterations in cell surface markers also occurred with vandetanib treatment, suggesting induction of differentiation. In combination with DNA damaging agents (etoposide and doxorubicin) vandetanib demonstrated synergistic induction of cell death. However in combination with the anti-metabolite methotrexate, vandetanib had an antagonistic effect on cell death. Although several targets of vandetanib are expressed on acute leukemia cell lines, expression of vandetanib targets did not predict vandetanib sensitivity and alone are therefore not likely candidate biomarkers in patients with acute leukemia. Interactions between vandetanib and standard chemotherapy agents in vitro may help guide choice of combination regimens for further evaluation in the clinical setting for patients with relapsed/refractory acute leukemia. Taken together, these preclinical data support clinical evaluation of vandetanib, in combination with cytotoxic chemotherapy, for pediatric leukemia.

Recently, aberrant coexpression of CD2 and CD25 has been reported to reliably distinguish neoplastic mast cells from normal or so-called reactive mast cells. Such expression is included in the consensus diagnostic criteria for systemic mast cell disease (SMCD). In our study of patients with SMCD, we found CD2 expression to be more prevalent on mast cells from patients without an associated haematological disorder (P = 0.04). Furthermore, no correlation was found between mast cell CD2 expression and other clinicopathological features in these patients.

Human hematopoietic stem cells (HSCs) and progenitors can be isolated by enriching for a rare cell population with a combination of monoclonal antibodies (MAbs). Such an isolation scheme involves multi-step procedures including ficoll-density fractionation and presort enrichment followed by cell sorting. Over the past decade, various cell-surface and metabolic markers have been identified and used to isolate human HSCs and progenitors as summarized in Table 1. Among them, CD34 has become the most critical cell-surface marker for positively selecting a rare cell population (1,2). Within the CD34(+) cell population, the differential expression of Thy-1, CD38, and AC133 have been used to fractionate HSCs and progenitors. In order to subfractionate CD34(+) cells by these markers, the cells can be further purified by flow cytometry. HSCs can be further enriched into a Thy-1(+) (3-7), CD38(-lo) (8-10), Thy-1+ CD38(-lo) (11), or AC133+ (12,13) fraction of CD34(+) cells. Table 1 Commercially Available Cell-Surface and Metabolic Markers for Isolation of Human HSC and Progenitor Cells Marker Expression/Remark Fluorochrome conjugate recommended Reference Positive marker CD34 Positive FITC, PE, APC, BIO 1,2,33 Thy-1 Positive PE, BIO 3,4 AC133 Positive PE 12,34 Negative/low marker CD38 Negative /low FITC, PE, APC 8,9 HLA-DR( a ) Negative to low FITC, PE 35,36 Mature lineage marker, Lin- CD2 T-cell lineage FITC, PE, BIO 3 CD3 T-cell lineage FITC, PE, APC, BIO 3 CD19 B-cell lineage FITC, PE, APC, BIO 3 CD16 NK-cell lineage FITC, PE, APC, BIO 3 CD14 Myeloid lineage FITC, PE 3 CD15 Myeloid lineage FITC, PE 3 Glycophorin A Erythroid lineage FITC, PE 3 2nd Step reagent Avidin/Streptavidin For BIO MAb FITC, PE, APC, TXRD, PharRed, Cy-chrome( d ) Metabolic marker( b ) Rhodamine 123( c ) Low Mitochondria-binding dye 37,38 Hoechst 33342( c ) Low DNA-binding dye 39,40 Pyronin Y Low RNA-binding dye 39,40 Propidium iodide Negative to low Dead-cell exclusion Abbreviations: FBM, fetal bone marrow; MPB, mobilized peripheral blood; ABM, adult bone marrow; HSC, hematopoietic stem cells; FITC, fluorescein; PE, phycoerythrin; APC, allophycocyanin; TXRD, Texas red; BIO, biotinylated. ( a ) FBM, MPB HSCs express HLA-DR (41,42). ( b ) To isolate quiescent HSC. ( c ) Substrates for p-glycoprotein, encoded by MDR-1. HSC possess high levels of p-glycoprotein efflux activity. ( d ) Recommended for single laser flow cytometry only, lineage marker positive and PI positive cells can be excluded simultaneously.