Analysis of abnormal clones by the fluorescent aerolysin method in paroxysmal nocturnal haemoglobinuria and other marrow disorders

INTRODUCTION

Flow cytometry is the most sensitive and specific diagnostic modality for the assessment of clone size in paroxysmal nocturnal haemoglobinuria (PNH) and other bone marrow failure states. In this study, we attempt to distinguish PNH from aplastic anaemia (AA) and myelodysplastic syndromes (MDS) associated with PNH clones at diagnosis by clone size, clinical and laboratory features.

METHODS

A total of 29 samples included 19 PNH cases and 10 AA/MDS cases with PNH clones. Flow cytometry was performed using fluorescent aerolysin (FLAER)-based assay and comparison of clinical features, laboratory parameters and PNH clone size was carried out at diagnosis.

RESULTS

The PNH clone size on granulocytes varied from 0.4% to 99.2% and correlated with the clone size on monocytes (r = 0.966; P < 0.001). Paroxysmal nocturnal haemoglobinuria clone size on granulocytes (median = 34.6%) and monocytes (median = 49.9%) was always larger than erythrocytes (median = 10.9%). The median clone size in PNH (median granulocytes = 74.9%, monocytes = 71.8%) was significantly greater than in AA/MDS associated with PNH clone (median granulocytes = 2.9%, monocytes = 6%). In PNH patients, a significant negative correlation was seen between PNH clone on monocytes and the haemoglobin concentration.

CONCLUSION

In our small study using the FLAER method, the clone size was >70% in majority of PNH cases. In other marrow disorders like AA/MDS, the clone size was usually <10%.

Is CD20 positive plasma cell myeloma a unique clinicopathological entity? A study of 40 cases and review of the literature

AIMS

A number of clinicopathological features have been attributed to the CD20 positive subset of plasma cell myeloma (PCM). CD20 is an appealing therapeutic target given the success with monoclonal antibody regimens in a spectrum of B cell lymphomas. To date, a small number of reports have described CD20 PCM as a unique subset, and these are not conclusive, especially taking into consideration reporting bias. This study aims to further identify the clinicopathological features of CD20 PCM.

METHODS

A retrospective analysis of all newly diagnosed PCM between 2003 and 2010 was undertaken. Trephine material was retrieved and reviewed for CD20, and for positive cases an extended immunohistochemical (IHC) panel including cyclin D1 was subsequently performed.

RESULTS

The review of our 40 cases and those described in the literature demonstrated that these are heterogeneous with regard to clinical features, morphology, biochemical features, immunophenotype, and cytogenetics.

CONCLUSION

Based on our study and review of the literature, CD20 PCM cases represent a heterogeneous disease and not a unique clinicopathological entity.

Is serial testing required to diagnose imported malaria in the era of rapid diagnostic tests?

Exclusion of malaria traditionally requires three negative serial thick and thin blood films. However, many clinical laboratories now routinely perform rapid diagnostic tests (RDTs) in addition to blood films when malaria is suspected. We sought to determine whether serial testing is necessary in this setting. We examined 388 cases of malaria diagnosed during 1999-2010 at three laboratories in Melbourne, Australia. For each case, we ascertained whether the diagnosis was made on initial or follow-up testing. Nine cases (3.5%) were diagnosed after a negative initial blood film and RDT: 7 Plasmodium vivax, 1 P. ovale, and 1 P. falciparum. Of four case-patients with P. vivax in which clinical data were available, all had recent exposure to antimalarial medication. Our data suggest that among patients who have not received recent anti-malarial therapy, and when RDTs are performed and blood films are prepared, most malaria diagnoses are made by using the first set of tests.

Detection of BRAF mutations in patients with hairy cell leukemia and related lymphoproliferative disorders

Hairy cell leukemia has been shown to be strongly associated with the BRAF V600E mutation. We screened 59 unenriched archived bone marrow aspirate and peripheral blood samples from 51 patients with hairy cell leukemia using high resolution melting analysis and confirmatory Sanger sequencing. The BRAF V600E mutation was detected in 38 samples (from 36 patients). The BRAF V600E mutation was detected in all samples with disease involvement above the limit of sensitivity of the techniques used. Thirty-three of 34 samples from other hematologic malignancies were negative for BRAF mutations. A BRAF K601E mutation was detected in a patient with splenic marginal zone lymphoma. Our data support the recent finding of a disease defining point mutation in hairy cell leukemia. Furthermore, high resolution melting with confirmatory Sanger sequencing are useful methods that can be employed in routine diagnostic laboratories to detect BRAF mutations in patients with hairy cell leukemia and related lymphoproliferative disorders.

First isolations in India of Candida nivariensis, a globally emerging opportunistic pathogen

We randomly screened 363 yeast isolates during 2008 for their ability to form white colonies on CHROM agar Candida medium. Two of these isolates (0.5%) were identified as Candida nivariensis based on detailed phenotypic characterization and DNA sequencing. One was recovered from the sputum of an HIV-positive patient with a pneumonic lesion and the second from the blood of a diabetic with oropharyngeal lesions. Direct DNA sequencing of the D1/D2 region of 28S rRNA gene and/or the internal transcribed spacer (ITS) regions of rDNA confirmed that both of the isolates were C. nivariensis. The carbohydrate assimilation profiles with the ID 32 C and VITEK 2 yeast identification systems revealed only glucose assimilation. In vitro antifungal susceptibility profiles by broth microdilution and Etest methods revealed susceptibility of both isolates to fluconazole, itraconazole, voriconazole, amphotericin B and 5-flucytosine, with low MICs for posaconazole and caspofungin. These results document the occurrence of Candida nivariensis for the first time in India and focus on its potential as an opportunistic human pathogen.

Mentoring in the management of hematological malignancies

AIM

The Mentoring in Management of Haematological Malignancies (MMHM) project aimed to improve treatment outcomes, coordinate care and provide best practice for patients with hematological cancers, by developing a program of mentoring and multidisciplinary care between a regional and a metropolitan centre.

METHODS

A regular multidisciplinary meeting conducted by teleconference was established between a tertiary metropolitan site and a regional practice to discuss cases of patients with hematological malignancies. Information from multidisciplinary team meetings was recorded to capture adherence to process and clinician outcomes. An educational program was developed. A gap analysis was performed to identify differences in routine practice between the two centers. Clinician satisfaction with mentoring and educational interventions was assessed by structured survey.

RESULTS

The MMHM project developed a formal mentoring system to improve the management of patients by building on established links and developing an innovative model of web-based multidisciplinary care. The project established a novel multidisciplinary meeting between a metropolitan and regional site. Common treatment policies were adopted between the two sites. Development of an educational framework and mentoring for health-care professionals in regional areas was achieved by tutorials and workshops. Most participating clinicians indicated their high level of satisfaction with the mentoring project.

CONCLUSION

The MMHM project was a successful pilot of a mentoring program in hematological cancers between metropolitan and regional centers that resulted in improved referral links, facilitated better care coordination, updated treatment policies and guidelines and increased clinician satisfaction and knowledge.

Leukaemic Subtype of Marginal Zone Lymphoma: A Presentation of Three Cases and Literature Review

The recent World Health Organization (WHO) classification recognizes three subtypes of marginal zone lymphoma (MZL): extranodal MZL of mucosa-associated lymphoid tissue (MALT), splenic MZL and nodal MZL. As a group, MZL share morphological and immunophenotypic features similar to that of the marginal zone B-cell in secondary B-follicles, the postulated common cell of origin. There is, however, increasing information about molecular heterogeneity between the types of MZL, suggesting different aetiology and highlighting our current incomplete understanding of this evolving entity. We describe the presentation and clinical course of three patients with MZL who do not fit the currently recognized WHO categories, and best fit the putative category of MZL, leukaemic subtype. We review the current literature on this newly described entity, highlighting the importance of its recognition.

Immunohistochemistry is a more sensitive marker for the detection of myeloperoxidase in acute myeloid leukemia compared with flow cytometry and cytochemistry

Myeloperoxidase (MPO) is an unequivocal marker of myeloid differentiation which is routinely detected using cytochemistry (CC), flow cytometry (FC) and immunohistochemistry (IH). Several studies have compared the use of two of these methods, but to our knowledge none has compared all three techniques. We compared the performance of these three modalities in the detection of MPO in 158 cases of acute myeloid leukaemia (AML). Discrepancies were noted in a total of 28 cases. Of 110 cases in which all three modalities were performed, 23 cases showed discrepancies. CC was the least sensitive marker, being negative in 11 of 23 cases in the presence of positive IH and/or FC. IH was the most sensitive marker with only one case being negative in the presence of a positive result by FC and/or CC. The results highlight the necessity of employing more than one method in determining the presence of MPO and confirm the important role of IH in the diagnosis of AML particularly in cases where MPO is not detected by CC and FC.

Detection of NPM1 exon 12 mutations and FLT3 - internal tandem duplications by high resolution melting analysis in normal karyotype acute myeloid leukemia

Background

Molecular characterisation of normal karyotype acute myeloid leukemia (NK-AML) allows prognostic stratification and potentially can alter treatment choices and pathways. Approximately 45–60% of patients with NK-AML carry NPM1 gene mutations and are associated with a favourable clinical outcome when FLT3-internal tandem duplications (ITD) are absent. High resolution melting (HRM) is a novel screening method that enables rapid identification of mutation positive DNA samples.

Results

We developed HRM assays to detect NPM1 mutations and FLT3-ITD and tested diagnostic samples from 44 NK-AML patients. Eight were NPM1 mutation positive only, 4 were both NPM1 mutation and FLT3-ITD positive and 4 were FLT3-ITD positive only. A novel point mutation Y572C (c.1715A>G) in exon 14 of FLT3 was also detected. In the group with de novo NK-AML, 40% (12/29) were NPM1 mutation positive whereas NPM1 mutations were observed in 20% (3/15) of secondary NK-AML cases. Sequencing was performed and demonstrated 100% concordance with the HRM results.

Conclusion

HRM is a rapid and efficient method of screening NK-AML samples for both novel and known NPM1 and FLT3 mutations. NPM1 mutations can be observed in both primary and secondary NK-AML cases.