A method is described for the analysis of chromosomes in prophase and early metaphase. It involves culturing the lymphocytes in medium RPMI-1640, supplemented with 10% autologous plasma instead of fetal bovine serum. Living cells are treated with actinomycin D and colcemid for 1 h prior to harvest and harvested early at 65 h of incubation, using a hypotonic solution formulated by Ohnuki (1968). The method has been tested on several hundred clinical samples on a routine basis. On average, 30% of the dividing cells were in prometaphase.

B-lymphoblastic leukemia (a.k.a. precursor B-cell acute lymphoblastic leukemia) is a heterogeneous disease at the clinical, morphologic, immunophenotypic and genetic levels. Recurrent genetic abnormalities in B-lymphoblastic leukemia with prognostic significance are well known and specifically delineated in the WHO 2008 classification (eg hyperdiploidy, t(9;22)(q34;q11.2); BCR-ABL1, t(12;21)(p13;q22); ETV6-RUNX1). In recent years, a subgroup of B-lymphoblastic leukemia with the recurring genetic alteration of RUNX1 amplification has emerged. This subgroup has a low incidence (2%) and an increased risk of relapse and overall worse outcome. Given these apparently distinctive clinicopathologic features, we evaluated eight cases of pediatric B-lymphoblastic leukemia with RUNX1 amplification treated on Children's Oncology Group protocols from 2000-2009. Compared with 25 consecutive B-lymphoblastic leukemia cases without RUNX1 amplification, we identified a trend toward male predominance (P-value ¼ 0.082) and low white blood cell count at presentation (P-value ¼ 0.081) in B-lymphoblastic leukemia with RUNX1 amplification. Older age at presentation was significant (median age 9.5 years, P-value ¼ 0.006). There was no significant difference in the presence of central nervous system disease, CD20 or myeloid antigen positivity on the blasts or percent circulating blasts in B-lymphoblastic leukemia with RUNX1 amplification versus other B-lymphoblastic leukemia types. Seven of eight patients (88%) are alive and free of disease at the time of last checkup (mean 50 months, range 14-116 months). Although we see a relatively good outcome in our small cohort of patients, recent findings from the Children's Oncology Group on a large set of patients suggests otherwise that these patients may have an inferior outcome compared with patients with B-lymphoblastic leukemia without RUNX1 amplification. Longterm follow-up in larger cohorts including minimal residual disease correlation is required. Modern Pathology (2011Pathology ( ) 24, 1606Pathology ( -1611 doi:10.1038/modpathol.2011; published online 5 August 2011Keywords: acute leukemia; AML1; amplification; B-lymphoblastic leukemia; precursor B-cell; RUNX1 B-lymphoblastic leukemia (a.k.a. precursor B-cell acute lymphoblastic leukemia) is a heterogeneous disease at the clinical, morphologic, immunophenotypic and genetic levels. Despite modern therapies targeted against a combined risk assessment of age, white blood cell count, central nervous system involvement, early/slow treatment response, genetics and minimal residual disease, B20% of children experience disease recurrence. Continued refinement of therapeutic protocols and risk-stratification categories are necessary for further improving B-lymphoblastic leukemia response rates. Recurrent genetic abnormalities in B-lymphoblastic leukemia with prognostic significance are well known and are specifically categorized in the WHO 2008 classification.1 These distinct genetic subgroups of B-lymphoblastic leukemia include hyperdiploidy, h...

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Certain lymphoma types are characterized by recurring genetic translocations. Detection of these translocations enables confirmation of a suspected diagnosis and provides a genetic marker which can be subsequently monitored and followed. Rapid and reliable identification of these molecular rearrangements is a key component in the workup of lymphoma. While conventional cytogenetics may be a useful tool in this regard, fluorescence in situ hybridization (FISH) offers additional advantages including the ability to use formalin-fixed tissues, no requirement for dividing cells, ability to score many cells, improved sensitivity, and faster turnaround time for results.