Biomarker testing in oncology - Requirements for organizing external quality assessment programs to improve the performance of laboratory testing: revision of an expert opinion paper on behalf of IQNPath ABSL.

In personalized medicine, predictive biomarker testing is the basis for an appropriate choice of therapy for patients with cancer. An important tool for laboratories to ensure accurate results is participation in external quality assurance (EQA) programs. Several providers offer predictive EQA programs for different cancer types, test methods, and sample types. In 2013, a guideline was published on the requirements for organizing high-quality EQA programs in molecular pathology. Now, after six years, steps were taken to further harmonize these EQA programs as an initiative by IQNPath ABSL, an umbrella organization founded by various EQA providers. This revision is based on current knowledge, adds recommendations for programs developed for predictive biomarkers by in situ methodologies (immunohistochemistry and in situ hybridization), and emphasized transparency and an evidence-based approach. In addition, this updated version also has the aim to give an overview of current practices from various EQA providers.

Crizotinib inhibition of ROS1-positive tumours in advanced non-small-cell lung cancer: a Canadian perspective.

The ros1 kinase is an oncogenic driver in non-small-cell lung cancer (nsclc). Fusion events involving the ROS1 gene are found in 1%-2% of nsclc patients and lead to deregulation of a tyrosine kinase-mediated multi-use intracellular signalling pathway, which then promotes the growth, proliferation, and progression of tumour cells. ROS1 fusion is a distinct molecular subtype of nsclc, found independently of other recognized driver mutations, and it is predominantly identified in younger patients (<50 years of age), women, never-smokers, and patients with adenocarcinoma histology. Targeted inhibition of the aberrant ros1 kinase with crizotinib is associated with increased progression-free survival (pfs) and improved quality-of-life measures. As the sole approved treatment for ROS1-rearranged nsclc, crizotinib has been demonstrated, through a variety of clinical trials and retrospective analyses, to be a safe, effective, well-tolerated, and appropriate treatment for patients having the ROS1 rearrangement. Canadian physicians endorse current guidelines which recommend that all patients with nonsquamous advanced nsclc, regardless of clinical characteristics, be tested for ROS1 rearrangement. Future integration of multigene testing panels into the standard of care could allow for efficient and cost-effective comprehensive testing of all patients with advanced nsclc. If a ROS1 rearrangement is found, treatment with crizotinib, preferably in the first-line setting, constitutes the standard of care, with other treatment options being investigated, as appropriate, should resistance to crizotinib develop.

ICSH guidelines for the standardization of bone marrow immunohistochemistry.

Bone marrow (BM) tissue biopsy evaluation, including trephine biopsy and clot section, is an integral part of BM investigation and is often followed by ancillary studies, in particular immunohistochemistry (IHC). IHC provides in situ coupling of morphological assessment and immunophenotype. The number of different IHC tests that can be applied to BM trephine biopsies and the number of indications for IHC testing is increasing concurrently with the development of flow cytometry and molecular diagnostic methods. An international Working Party for the Standardization of Bone Marrow IHC was formed by the International Council for Standardization in Hematology (ICSH) to prepare a set of guidelines for the standardization of BM IHC based on currently available published evidence and modern understanding of quality assurance principles as applied to IHC in general. The guidelines were discussed at the ICSH General Assemblies and reviewed by an international panel of experts to achieve further consensus and represent further development of the previously published ICSH guidelines for the standardization of BM specimens handling and reports.

Dominant-negative Ikaros cooperates with BCR-ABL1 to induce human acute myeloid leukemia in xenografts.

Historically, our understanding of mechanisms underlying human leukemogenesis are inferred from genetically engineered mouse models. Relatively, few models that use primary human cells recapitulate the full leukemic transformation as assayed in xenografts and myeloid transformation is infrequent. We report a humanized experimental leukemia model where xenografts develop aggressive acute myeloid leukemia (AML) with disseminated myeloid sarcomas within 4 weeks following transplantation of cord blood transduced with vectors expressing BCR-ABL1 and a dominant-negative isoform of IKAROS, Ik6. Ik6 induced transcriptional programs in BCR-ABL1-transduced progenitors that contained repressed B-cell progenitor programs, along with strong stemness, proliferation and granulocyte-monocytic progenitor (GMP) signatures-a novel combination not induced in control groups. Thus, wild-type IKAROS restrains stemness properties and has tumor suppressor activity in BCR-ABL1-initiated leukemia. Although IKAROS mutations/deletions are common in lymphoid transformation, they are found also at low frequency in AML that progress from a prior myeloproliferative neoplasm (MPN) state. Our experimental system provides an excellent model to gain insight into these rare cases of AML transformation and the properties conferred by IKAROS loss of function as a secondary mutation. More generally, our data points to the importance of deregulated stemness/lineage commitment programs in human myeloid leukemogenesis.

Call for a European programme in external quality assurance for bone marrow immunohistochemistry; report of a European Bone Marrow Working Group pilot study.

BACKGROUND AND AIMS: In diagnostic immunohistochemistry (IHC), daily quality control/quality assurance measures (QC/QA) and participation in external quality assurance programmes (EQA) are important in ensuring good laboratory practice and patient care. Bone marrow trephine biopsies (BMTB) have been generally excluded from EQA programmes for diagnostic IHC due to a lack of standards for tissue processing. The European Bone Marrow Working Group (EBMWG) has set up an EBMWG IHC Committee with the task of exploring the plausibility of an EQA programme for BMTB IHC in Europe. METHODS: 28 laboratories participated in a web-based anonymous survey; 19 laboratories submitted a total of 109 slides stained for CD34, CD117, CD20, CD3, Ki-67 and a megakaryocyte marker of choice. RESULTS: Eight different fixatives and nine different decalcification methods were used. While 93% of participants believed that they produced excellent results in BMTB IHC, only 4/19 (21%) laboratories did not have any poor results. CD117 and Ki-67, with 53% and 50% poor results, respectively, were the most problematic immunostains, while CD20 was the least problematic, with only 11% poor results. CONCLUSIONS: The EBMWG IHC Committee calls for a reduction in the tissue processing methods for BMTB and establishment of an EQA programme for BMTB IHC to help diagnostic IHC laboratories calibrate their tests according to expert recommendations. This is especially necessary in the light of recent introduction of predictive IHC tests in BMTB.

A marginal zone phenotype in follicular lymphoma with t(14;18) is associated with secondary cytogenetic aberrations typical of marginal zone lymphoma.

Marginal zone differentiation of follicular lymphomas (FL), sometimes referred to as monocytoid B-cell differentiation, is a relatively uncommon phenomenon. Recently, this type of differentiation was also linked to secondary cytogenetic aberrations of chromosome 3 in a small number of patients. We have analysed 131 primary nodal FL with t(14;18)(q32;q21) for secondary cytogenetic aberrations previously described as recurrent in marginal zone lymphomas (MZL) to identify their frequency and possible association with morphological evidence of marginal zone differentiation. We searched for trisomy of chromosomes 3, 12, and 18, gains of chromosome arm 3q, deletions of chromosome arm 7p, structural anomalies with break-points in 1q21 and 1p34, as well as the t(1;2)(p22;p12), t(1;14)(p22;q32), t(3;14)(q27;q32), t(6;14)(p21;q32), and t(11;18)(q21;q21) translocations. At least focal morphological evidence of marginal zone differentiation occurred in 35/131 (27%) FL with t(14;18)(q32;q21) as the primary chromosomal abnormality. None of the recurrent balanced translocations characteristic of extranodal MZL were seen secondarily in the nodal FLs with t(14;18)(q32;q21). However, 43/131 (33%) cases had at least one of the above secondary cytogenetic aberrations previously reported as recurrent aberrations in MZL and, when combined, these were significantly more frequent in FL with morphological evidence of marginal zone differentiation (p<0.0001, two-sided Fisher's exact test). Aberrations of chromosome 3 and, in particular, trisomy 3 occurred frequently in FL with marginal zone differentiation (p=0.002 and p<0.0001, respectively, two-sided Fisher's exact test), while chromosome 21, 22, and X chromosome aberrations, which have not been described previously as recurrent in MZL, were also significantly associated with marginal zone differentiation in FL (p=0.002, p=0.037, p=0.039, respectively, two-sided Fisher's exact test).

Prognostic significance of PU.1 in follicular lymphoma.

Very few prognostic factors are known in follicular lymphoma (FL), a common malignancy of germinal centre (GC) B-cells. The Follicular Lymphoma International Prognostic Index (FLIPI) thus far appears to be the most important predictor of clinical outcome. This study explores the predictive power of the degree of GC differentiation for outcome in FL. Samples from 73 patients with FL were evaluated by immunohistochemistry for expression of GC markers. Strong PU.1, CD20, and CD75 expression were significantly associated with longer progression-free survival (PFS) and overall survival (OS). Results for PFS were independent of the International Prognostic Index or the Italian Lymphoma Intergroup prognostic index for CD75 and PU.1, but only PU.1 expression was independent of FLIPI for PFS and OS. Oct-2 was weakly expressed overall, but more strongly in higher grades of FL; it had a trend for negative linear association with PU.1 and strong positive linear association with CD27, which possibly reflects its role in terminal B-cell differentiation. We show that the level of GC differentiation, as determined by the levels of PU.1, CD75, CD20, Bcl-6, and CD10 expression, has an association with outcome in patients with FL. While this is determined qualitatively in most studies of diffuse large B-cell lymphoma, in FL there is a quantitative positive association between a high level of expression of GC antigens and longer OS and PFS even when data are stratified by the FLIPI score.

Simultaneous bilateral breast carcinoma: Histopathological characteristics and CD44/catenin-cadherin profile.

AIMS: Family history of breast carcinoma, multicentric tumor foci in one breast, and in situ lobular carcinoma increase the risk of bilateral breast cancer (BBC), synchronous or metachronous. Synchronous tumors are designated as simultaneous breast carcinoma if they appear at the same time. The CD44 family and cadherin/catenin immunophenotype of this group of BBCs has not yet been evaluated. The aim of this study was to compare clinicopathological characteristics and immunohistochemical profiles of simultaneous BBC and corresponding lymph node metastases in eight patients. METHODS AND RESULTS: In toto 15 primary and 9 metastatic tumors were evaluated. The expression of CD44 variant isoforms, beta-catenin, E, P and N-cadherin were evaluated by immunohistochemistry. Rare types of breast carcinoma were frequent in this group of patients. There were 6 pleomorphic lobular, 5 invasive ductal of usual type, 3 atypical medullary carcinomas, 2 mucinous and one invasive micropapillary carcinoma. The expression CD44v6 was most frequent, followed by CD44v3-10, CD44v5, and CD44v3. CD44v4 was generally not expressed. E-cadherin was expressed in 80% primary tumors, 40% expressed N-cadherin, and 66% expressed P-cadherin. CONCLUSIONS: Generally, simultaneous carcinomas had different morphology and different immunophenotype. Each primary tumor was more similar to its corresponding metastatic tumor than to the contralateral primary tumor.

Prognostic implications of BCL6 rearrangement in uniformly treated patients with diffuse large B-cell lymphoma--a Nordic Lymphoma Group study.

The purpose of this study was to investigate the prognostic implications of BCL6 rearrangement in a uniformly treated population of patients with diffuse large B-cell lymphoma (DLBCL) and to characterise the relationship between BCL6 rearrangement and prognostic factors. A total of 269 patients with DLBCL entered a randomised trial comparing the chemotherapy regimen CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) to the MACOP-B (methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin) regimen. In 44 cases, frozen tissue was available for assessment of BCL6 status by Southern blot analysis. BCL6 was rearranged in six of 43 evaluable cases (14%), and was associated with elevated lactate dehydrogenase (LDH), and a higher patient age. No association between BCL6 status and expression of BCL2, Ki-67 or TP53 was found. Patients presenting with BCL6 rearrangement displayed a weak trend towards better overall and failure-free survival (67 and 67% at 5 years), compared to patients with germline BCL6 (63 and 52%), but the difference was not statistically significant. In accordance with previously published series, the presence of BCL6 rearrangement does not define a prognostically distinct subgroup of DLBCL. Assessment of BCL6 status may, however, be of clinical interest when related to other prognostic variables.

Cultured anaplastic cell lines as immunocytochemistry controls: a comparison of ThinPrep-processed smears and conventional air-dried cytospins.

Cultured anaplastic cell lines with previously characterized phenotypes are considered to be the best positive controls for immunocytochemistry. We assessed the validity of using anaplastic cell line cytospins as positive controls for immunocytochemistry performed on ThinPrep-processed clinical samples. We compared ThinPrep-processed slides and air-dried cytospins from cultured anaplastic cell lines for intensity and pattern of staining. Also, antigen preservation was assessed over a 3-mo period, using a panel of 16 primary antibodies and 12 anaplastic cell lines. A three-step alkaline phosphatase procedure was used except when in a single instance the EnVision method was employed. If appropriately stored, both preparations showed excellent correlation with no decrease in antigenicity during the 3-mo testing period. ThinPrep-processed slides from clinical samples are ideal for immunocytochemistry, because internal negative controls can be performed for each test. We recommend the use of cytospins for positive controls because of the lower cost.

The transcription factor PU.1, necessary for B-cell development is expressed in lymphocyte predominance, but not classical Hodgkin's disease.

Hodgkin's disease (HD) is a lymphoproliferative disease of predominantly B-cell origin. However, the reasons for the incomplete development of the B-cell phenotype and lack of immunoglobulin expression in classical HD (cHD) have not been fully explained. We examined the expression of PU.1 in HD, an Ets-family transcription factor, which regulates the expression of immunoglobulin and other genes that are important for B-cell development. Immunohistochemistry for PU.1 was performed on 35 cases of cHD and 15 cases of lymphocyte predominance HD as well as 67 non-Hodgkin's lymphomas (NHL). Expression of PU.1 was studied by Western blotting in four cHD-derived cell lines and in five NHL cell lines. We also studied the expression of two additional B-cell transcription factors, B-cell-specific activator protein and Oct-2. Our results show a striking lack of PU.1 expression by neoplastic cells in cHD but not in lymphocyte predominance HD. Our study also confirmed that B-cell-specific activator protein but not Oct-2 is not expressed by cHD. Western blotting showed no PU.1 protein expression in the cHD-derived cell lines, with the exception of one cell line of putative monocyte/histiocyte origin. The lack of PU.1 protein expression in cHD likely contributes to the lack of immunoglobulin expression and incomplete B-cell phenotype characteristic of the Reed-Sternberg cells in cHD.

Prognostic significance of histologic grading in patients with prostate carcinoma who are assessed by the Gleason and World Health Organization grading systems in needle biopsies obtained prior to radiotherapy.

BACKGROUND: The current study was conducted to evaluate and compare the impact of two major histologic grading systems on failure-free survival in patients with prostate carcinoma who are treated with definitive radiation. METHODS: Eligible patients for the current study had localized adenocarcinoma of the prostate (T1-4pN0M0, T3/4: 67%, median observation time: 69 months) and were treated with intent-to-cure external radiotherapy between 1989 and 1995. The specimens from 178 patients, obtained by needle biopsies, were reviewed simultaneously by two pathologists assigning World Health Organization (WHO) and Gleason grades. Three-tiered Gleason grouping distributed patients into three groups (those with a score < 7, those with a score of 7, and those with a score of 8--10), whereas two-tiered Gleason categorization distributed patients into two groups (those with a Gleason score of 7A, major 3 + minor 4 patients were added to the group of patients with a Gleason score < 7 and patients with a Gleason score of 7B, major 4 + minor 3 were added to the group of patients with a Gleason score of 8--10). Univariate and multivariate analyses were performed. A P value < 0.05 was considered to be statistically significant. RESULTS: Three-tiered Gleason grouping resulted in a relatively even distribution of the patients (44 patients had a Gleason score < 7, 58 patients had a Gleason score of 7, and 76 patients had a Gleason score of 8--10) whereas 130 patients were determined to have Grade 2 tumors based on WHO criteria. Separating those patients with a Gleason score of 7 (score 3+4 vs. score 4+3) led to the two-tiered Gleason grouping (88 patients in the favorable group and 90 patients in the unfavorable group). The two-tiered Gleason grouping displayed differences with regard to failure-free survival with the lowest P values for all patients and separately for T1/2 versus T3/4 tumors. Together with T category and pretreatment prostate specific antigen, WHO grading, three-tiered Gleason grouping, and two-tiered Gleason grouping resulted in independent parameters in the Cox regression model. The proportional variance estimate confirmed the superior discrimination for survival of two-tiered Gleason grouping. CONCLUSIONS: The equal allocation of patients to subgroups based on the Gleason system helps the clinician to overcome the dilemma of overrepresentation of Grade 2 patients as occurs with WHO grading. The Gleason grading system and, most likely, the two-tiered Gleason grouping appear to result in better prognostic separation of patients referred to radiotherapy for relatively advanced primary tumors. Therefore the authors recommend the routine use of Gleason grading for these patients.

CD34(+) cell enrichment depletes atypical CD30(+) cells from PBPC grafts in patients with HD.

BACKGROUND: European Group for Blood and Marrow Transplantation (EBMT) registry data indicate that patients with relapsed HD given high-dose therapy (HDT), supported with PBPC might have a poorer outcome compared with those given BM. Since this can be due to the infusion of contaminating tumor cells in the PBPC products, we studied the presence of minimal residual disease and tested whether CD34(+) cell enrichment was able to remove atypical CD30(+) cells from PBPC grafts. METHODS: Eighteen HD patients eligible for HDT were included in the study. By the use of immunocytochemistry (ICC), mononuclear cells from BM and peripheral blood (PB) before mobilization, PBPC products and selected CD34(+) fractions were stained using anti-CD30 MAb (Ber-H2) and the APAAP (alkaline phosphatase-anti-alkaline phosphatase) method. Cells scored as atypical CD30(+) cells were large- to medium-sized, with membranous, cytoplasmatic and/or Golgi positivity for CD30. RESULTS: Nine out of 11 BM tested were positive, while 14 of 14 PB and 18 of 18 PBPC contained atypical CD30(+) cells. The total number of atypical CD30(+) cells was significantly higher in PBPC than in the corresponding BM. CD34(+) cell enrichment employing ISOLEX 300I gave a purity and yield of 99.2% (range 97.8-99.7) and 49.6% (range 30.0-78.4), respectively. After HDT a median of 5.8 x 10(6) (range 2.7-20) CD34(+) cells/kg was infused. Neutrophil counts of > 0.5 x 10(9)/L and platelet counts of > 20 x 10(9)/L were achieved at Day 12 (range 10-17) and at Day 10 (range 7-15), respectively. Sixteen of 18 CD34(+) selected products had no detectable atypical CD30(+) cells, while two had a low number. After HDT, the overall survival was 80% and the event-free survival was 69%, with a median follow-up of 24 months (range 1-36). DISCUSSION: We show that contaminating atypical CD30(+) cells in PBPC can efficiently be removed by CD34(+) cell enrichment, and the use of such grafts following HDT gives fast and sustained engraftment.

High-dose therapy supported with immunomagnetic purged autologous bone marrow in high-grade B cell non-Hodgkin's lymphoma.

From August 1987 to March 1995, 25 patients with high-grade B cell non-Hodgkin's lymphoma (NHL) were treated with high-dose therapy (HDT) followed by bone marrow purged with immunomagnetic beads. At the time of transplantation, 20 patients were in sensitive relapse and five in first complete or partial remission. Ten patients had secondary high-grade NHL transformed from low-grade NHL. The HDT consisted of TBI followed by high-dose cyclophosphamide. All patients engrafted, except for two patients with early treatment-related death. Eleven patients relapsed, of whom nine died of lymphoma, and two are alive in new CR. The estimated event-free and overall survivals at 5 years were 40% and 48%, respectively, with a median follow-up of 48 months (range 1-123). Eight of the tumours contained the translocation t(14;18) at the major breakpoint region (MBR) of BCL-2. In these patients the presence of tumour cells in the bone marrow graft before and after purging were assessed by PCR. Four of five patients infused with non-detectable minimal residual disease in their autografts are in complete remission, while two of three patients reinfused with t(14;18) positive cells after purging, experienced a fast and aggressive relapse. As found by others, our data suggest that reinfusion of tumour-free autografts obtained by efficient in vivo purging using chemotherapy before harvesting, and/or by in vitropurging of the stem cell products, influence the patients remission status after HDT.

Detection of immunoglobulin heavy chain gene rearrangements by polymerase chain reaction analysis on lymph node imprints and fine-needle aspirate smears: a comparison of five different imprint preparations.

Five different preparations of lymph node imprints from 39 patients were studied to determine which preparations are suitable for obtaining interpretable results with polymerase chain reaction (PCR)-based detection of immunoglobulin heavy chain gene rearrangements and whether there are significant discrepancies in the patterns obtained. The sensitivity and specificity of this test for the diagnosis of B-cell lymphoma were assessed. The five imprints were stained with May-Grünwald-Giemsa (MGG) and coverslipped, stained with MGG but not coverslipped, fixed in acetone only, air-dried only, or immunostained, respectively. The efficiency of the PCR was 0% for immunocytochemically stained slides, 87% for air-dried only and air-dried/MGG-stained/coverslipped slides, 95% for air-dried/MGG-stained/not coverslipped slides, and 100% for imprints that were air-dried/acetone-fixed. There was total agreement in results in 87% cases studied. Discrepancies never resulted in false-positive test results. The overall sensitivity was 50%, and specificity was 100%. Based on these results, we have devised guidelines for tissue treatment when only stained slides are available. In a prospective study with 19 fine-needle aspirate specimens, the efficiency of the PCR increased to 100%, and sensitivity improved to 81%.

Uracil mustard revisited.

BACKGROUND: A patient with diffuse large cell lymphoma who had a complete response lasting 35 years following a 3-day course of uracil mustard stimulated a recall review of patients treated with this oral alkylating agent. METHODS: Records of patients treated with uracil mustard between 1958 and 1970 were reviewed. A current histologic review according to the International Formulation was performed when possible. Total doses of uracil mustard were similar to those of mechlorethamine, although there were variations in the dose schedule. RESULTS: Employing criteria used over 25 years ago to evaluate patients' responses, the overall regression rate for 94 non-Hodgkin lymphoma patients was 69.2% (complete response [CR] 23.4%). Of 62 patients with Hodgkin disease, 69.4% responded (CR 9.7%). For 39 patients with chronic lymphatic leukemia, the combined complete and partial response rate was 74% (CR 7.7%). Thrombocytopenia was the primary toxicity. CONCLUSIONS: Uracil mustard is an unmarketed, inexpensive oral alkylating agent that has been effective in the treatment of patients with lymphoma, chronic lymphatic leukemia, and thrombocythemia. Perhaps it should be reevaluated.

Evaluation of lymphoid cell populations in cytology specimens using flow cytometry and polymerase chain reaction.

Differential diagnosis between lymphomas and reactive lymphoid proliferations often requires ancillary techniques and morphologic evaluation. Flow cytometry (FCM) and polymerase chain reaction (PCR) can aid the detection of monoclonal B-cell populations. In the present study, the sensitivity and specificity of these two methods in the study of cytology specimens were compared. Eighty-six cytologic specimens from 81 patients (lymph nodes, solid organs, and body cavities) were evaluated. These specimens were taken from three groups of patients: those who underwent an initial evaluation for suspected lymphoma; those who were previously diagnosed with B-cell lymphoma and were now evaluated for possible disease recurrence; and those who were diagnosed with a nonhematologic malignancy. Histologic diagnosis was available for 51 samples. All samples were tested by FCM for the detection of monoclonality using kappa:lambda ratio and for clonal immunoglobulin heavy chain (IgH) gene rearrangements using a single-round PCR after cytologic evaluation. Tissue morphology, FCM and PCR results, and clinical findings in specimens without histologic diagnosis were correlated. Histologic evaluation (N = 51) revealed 44 specimens with B-cell malignancy. Twenty of the 44 lymphoma specimens (45%) were accurately diagnosed in cytologic smears, 18 (41%) were classified as suspicious of lymphoma, and 6 (14%) were diagnosed as reactive. FCM had superior sensitivity compared with PCR (77% vs. 64%). Fifty-six percent of specimens with B-cell malignancy were FCM+/PCR+, 23% were FCM+/PCR-, 14% were FCM-/PCR+, and 7% were FCM-/PCR-. The combined use of FCM and PCR resulted in a diagnosis of B-cell lymphoma in 41 (93%) of 44 B-cell lymphoma specimens and increased the sensitivity of fine needle aspiration by 48%. Both FCM and PCR aid in the diagnosis of lymphoid lesions in cytology specimens, and both can detect monoclonal B-cell populations that may be interpreted in cytology smears as reactive, even by experienced cytologists. Although FCM had higher sensitivity than PCR test in the present study, their combined use should be considered because of a relatively large number of specimens that were detected as monoclonal only with PCR.

Demonstration of clonality in neutrophils using FISH in a case of chronic neutrophilic leukemia.

A patient previously diagnosed with chronic neutrophilic leukemia (CNL) was studied using fluorescent in situ hybridization (FISH) to determine clonality of neutrophils. By cytogenetic studies the patient's blood and bone marrow had an 11q14 deletion and were negative for the Philadelphia (Ph) chromosome. FISH was performed on peripheral blood smears using probes for the bcr/abl translocation and a probe for 11q23 (MLL). The patient's white blood cells were negative for the bcr/abl translocation; neutrophils and eosinophils, but not lymphocytes, were monosomic for the 11q23 probe indicating a clonal population within the neutrophil population.