Clinical utility of FISH analysis in addition to G-banded karyotype in hematologic malignancies and proposal of a practical approach

Conventional Karyotyping and Fluorescence In Situ Hybridization for Detection of Chromosomal Abnormalities in Multiple Myeloma

Background

Multiple myeloma (MM) is a genetically heterogeneous disease, with cytogenetic findings that determine disease behavior. Genetic abnormalities can be assessed by fluorescence in situ hybridization (FISH) analysis and/or G-banded karyotyping. The two methods produce unique and overlapping information, and the clinical utility of using both is investigated here.

Methods

Seventy patients diagnosed with MM at a hospital in Southern California were retrospectively reviewed for the FISH and G-banded karyotyping results obtained from bone marrow specimens.

Results

Karyotype was normal in 71% (50/70), abnormal in 27% (19/70), and inadequate in 1% (1/70). Among patients with abnormal karyotype, FISH provided additional information about genetic aberrations in 95% of cases (18/19). Among cases with abnormal FISH, karyotype provided additional information about genetic aberrations in 27% of cases (18/66). When numerical abnormalities were present (detected by FISH and/or karyotype), FISH detected them in 95% (54/57), of which karyotype missed 70% (38/54) of the time. Karyotyping detected numerical abnormalities in 33% (19/57), which FISH missed 16% (3/19) of the time.

Conclusions

Karyotyping and FISH analysis in MM each provide unique information. For most patients, performing both tests together will provide more information than either test alone.

Identification of a new cryptic PML-RARα fusion gene without t(15;17) and biallelic CEBPA mutation in a case of acute promyelocytic leukemia: a case detected only by RT-PCR but not cytogenetics and FISH

Acute promyelocytic leukemia (APL) is characterized by the presence of promyelocytic leukemia-retinoic acid receptor α (PML-RARα) fusion gene, which is formed following the specific chromosomal translocation t(15;17)(q22;q21). However, cases with PML-RARα generated by occult t(15;17) which are negative by both cytogenetics and fluorescence in situ hybridization (FISH), are difficult to diagnose, leading to impaired treatment effectiveness. In the present study, we reported a case of a 66-year-old male patient, and bone marrow morphology, flow cytometry and cytogenetics did not support the diagnosis of APL. Molecular techniques, such as reverse-transcription polymerase chain reaction (RT-PCR), showed the existence of a cryptic PML-RARα fusion gene, and sequence analysis revealed a new variable isoform. Hotspot gene mutation analysis showed a biallelic CEBPA mutation. He received IA chemotherapy and all-trans retinoic acid (ATRA) treatment, and finally achieved complete remission. This case report provided valuable insights into the relevance of the correct identification of atypical PML-RARα fusion gene and biallelic CEBPA mutation. Moreover, combination of IA chemotherapy and ATRA treatment suggested a good clinical effect in this atypical PML-RARα.

Comparison of Diagnostic Yield of a FISH Panel Against Conventional Cytogenetic Studies for Hematological Malignancies: A South Indian Referral Laboratory Analysis Of 201 Cases

Objectives:

Genetic markers are crucial fort diagnostic and prognostic investigation of hematological malignancies (HM). The conventional cytogenetic study (CCS) has been the gold standard for more than five decades. However, FISH (Fluorescence in Situ Hybridization) testing has become a popular modality owing to its targeted approach and the ability to detect abnormalities in non-mitotic cells. We here aimed to compare the diagnostic yields of a FISH panel against CCS in HMs.

Methods:

Samples of bone marrow and peripheral blood for a total of 201 HMs were tested for specific gene rearrangements using multi-target FISH and the results were compared with those from CCS.

Results:

Exhibited a greater diagnostic yield with a positive result in 39.8% of the cases, as compared to 17.9% of cases detected by CCS. Cases of chronic lymphocytic leukaemia (CLL) benefited the most by FISH testing, which identified chromosomal aberrations beyond the capacity of CCS. FISH was least beneficial in myelodysplastic syndrome (MDS) where the highest concordance with CCS was exhibited. Acute lymphocytic leukaemia (ALL) demonstrated greater benefit with CCS. In addition, we found the following abnormalities to be most prevalent in HMs by FISH panel testing: RUNX1 (21q22) amplification in ALL, deletion of D13S319/LAMP1 (13q14) in CLL, CKS1B (1q21) amplification in multiple myeloma and deletion of EGR1/RPS14 (5q31/5q32) in MDS, consistent with the literature.

Conclusions:

In conclusion, FISH was found to be advantageous in only a subset of HMs and cannot completely replace CCS. Utilization of the two modalities in conjunction or independently should depend on the indicated HM for an optimal approach to detecting chromosomal aberrations.

Therapy-related myeloid neoplasm in an 18-year-old boy with B-lymphoblastic leukemia

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Acute myeloid leukemia or myelodysplastic syndrome during the course of ALL is a rare entity. Some of these cases are therapy-related while the others occur due to lineage switch. The correct diagnosis relies on comparing the immunophenotypes and cytogenetic/molecular alterations of the myeloid neoplasm and the ALL. We present the clinical, pathologic and cytogenetic features of a case of an 18-year-old male with prior treatment for B-lymphoblastic leukemia (B-ALL) who developed therapy-related myeloid neoplasm (t-MN) 4-5years after his initial diagnosis of B-ALL.

CASE PRESENTATION

A 13-year-old boy with no significant past medical history presented to Harbor-UCLA Medical Center (HUMC) in November 2012 with night sweats, fevers and chills, nausea, vomiting, diarrhea, fatigue, weakness, and weight loss. Peripheral blood flow cytometric analysis disclosed B-ALL. The blasts expressed CD10, CD19, CD22 (dim), CD34, CD38, HLA-DR, and TdT, and were negative for CD20, CD13, CD33, CD117, and cytoplasmic MPO. Chromosomal analysis and a supplemental fluorescence in situ hybridization (FISH) study performed on the bone marrow aspirate showed an abnormal karyotype (47,XY,+X,del(9)(p21p21)[4]/46,XY[16]). He achieved remission after induction chemotherapy and remained in remission until March 2016 when bilateral testicular masses were noted. Biopsy of the left testicular mass showed relapsed B-ALL. Cerebrospinal fluid (CSF) contained rare TdT-positive blasts, suggestive of minimal/early involvement by B-ALL. However, there was no evidence of acute leukemia in his bone marrow at this time. He was then treated with COG protocol AALL1331 randomized to blinatumomab arm and achieved second remission. In June 2017, the patient's peripheral blood smear showed 11% circulating monoblasts. By flow cytometry, the blasts expressed CD4, CD11b, CD13, CD15, CD33, CD38, CD56, and CD64. In addition, a few TdT-positive blasts were seen in his CSF cytospin smear. Bone marrow biopsy was subsequently performed which was consistent with evolving acute myeloid leukemia. A diagnosis of myeloid neoplasm, consistent with t-MN was made. Chromosomal analysis and FISH studies performed on his bone marrow aspirate showed normal karyotype (46,XY[20]), negative FISH result for deletion 9p21 locus, and positive KMT2A (MLL) rearrangement, respectively. Despite of chemotherapy, the patient died within one month after diagnosis.

DISCUSSION AND CONCLUSION

Diagnosis of t-MN should be suspected in patients with a history of receiving cytotoxic agents and/or irradiation. In this case study, we diagnosed t-MN with KMT2A rearrangement in a patient with history of B-ALL with 9p deletion and gain of X chromosome. Unusual features associated with this case are discussed.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology

CONTEXT

- A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia.

OBJECTIVE

- To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage.

DESIGN

- The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus.

RESULTS

- Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported.

CONCLUSIONS

- The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

Prognostic classification of MDS is improved by the inclusion of FISH panel testing with conventional cytogenetics

Cytogenetics is a critical independent prognostic factor in myelodysplastic syndromes (MDS). Conventional cytogenetics (CC) and Fluorescence in situ hybridization (FISH) Panel Testing are extensively used for the prognostic stratification of MDS, although the FISH test is not yet a bona fide component of the International Prognostic Scoring System (IPSS). The present study compares the utility of CC and FISH to detect chromosomal anomalies and in prognostic categorization. GTG-Banding and FISH Panel Testing specifically for -5/-5q, -7/-7q, +8 and -20q was performed on whole blood or bone marrow samples from 136 patients with MDS. Chromosomal anomalies were found in 40 cases by CC, including three novel translocations. FISH identified at least one anomaly in 54/136 (39.7%) cases. More than one anomaly was found in 18/54 (33.3%) cases, therefore, overall FISH identified 75 anomalies of which 32 (42.6%) were undetected by CC. FISH provided additional information in cases with CC failure and in cases with a normal karyotype. Further, in ten cases with an abnormal karyotype, FISH could identify additional anomalies, increasing the number of abnormalities per patient. Although CC is the gold standard in the cytogenetic profiling of MDS, FISH has proven to be an asset in identifying additional abnormalities. The number of anomalies per patient can predict the prognosis in MDS and hence, FISH contributed towards prognostic re-categorization. The FISH Panel testing should be used as an adjunct to CC, irrespective of the adequacy of the number of metaphases in CC, as it improves the prognostic classification of MDS.

Evaluation of Testing of Acute Leukemia Samples: Survey Result From the College of American Pathologists

CONTEXT

- The classification and prognosis determination in acute leukemia (AL) are complex and it is unclear what testing is being performed in practice.

OBJECTIVE

- To survey physicians describing their current practice of test ordering in the diagnosis of AL.

DESIGN

- In anticipation of a guideline by the College of American Pathologists (CAP) and the American Society for Hematology on laboratory testing needed for the initial workup of AL, a baseline survey was designed by an expert panel from CAP. Members of professional societies were asked to describe their current practice of test ordering.

RESULTS

- Two hundred ninety-four responses were received with 258 respondents analyzed after the first qualifying survey question regarding initial diagnosis of AL. One hundred seventy-six of 249 respondents (70.7%) were board-certified hematopathologists. Flow cytometry and karyotype analysis were routinely performed for acute myeloid leukemia (AML) (99.1% [232 of 234] and 96.2% [225 of 234], respectively) and acute lymphoblastic leukemia (ALL) (98.3% [229 of 233] and 96.6% [225 of 233], respectively). In addition, fluorescence in situ hybridization studies were routinely performed by 81.2% (190 of 234) of respondents for AML and 85.0% (198 of 233) of respondents for ALL; other molecular studies were performed by 78.2% (183) for AML and 54.9% (128) for ALL; immunohistochemistry by 44.9% (105) for AML and 47.6% (111) for ALL; and cytochemistry by 24.8% (58) for AML and 14.2% (33) for ALL.

CONCLUSIONS

- While flow cytometry and karyotyping are routinely reported as being performed for the diagnosis of AL, there is marked variation in the reporting of testing patterns for other genetic studies, immunohistochemistry, and cytochemistry.

Significance of ETV6 rearrangement in acute promyelocytic leukemia with t(15;17)/promyelocytic leukemia/retinoic acid receptor alpha

Acute promyelocytic leukemia (APL) is a common subtype of acute myeloid leukemia in China. Since the application of arsenic trioxide and all-trans retinoic acid in the treatment of APL, the prognosis has greatly improved. However, ~20% of patients with APL relapse upon completing chemotherapy. Decreasing the relapse rate and incidence of early mortality may pose the greatest challenges for the future management of APL. Recently, Ets variant 6 (ETV6) was reported to be involved in a variety of translocations associated with hematological malignancies of myeloid and lymphoid origin. To date, little is known about the clinical implication of ETV6 rearrangement in APL. In the present study, ETV6 rearrangement was examined by split-signal fluorescence in situ hybridization in 258 adults with APL, and its association with the clinical features and outcomes of the patients was analyzed. The data suggested that ETV6 rearrangement may be an independent unfavorable prognostic factor for overall survival in APL patients.

The progress of early growth response factor 1 and leukemia

Early growth response gene-1 (EGR1) widely exists in the cell nucleus of such as, zebrafish, mice, chimpanzees and humans, an it also can be observed in the cytoplasm of some tumors. EGR1 was named just after its brief and rapid expression of different stimuli. Accumulating studies have extensively demonstrated that the widespread dysregulation of EGR1 is involved in hematological malignancies such as human acute myeloid leukemia (AML), chronic myelogenous leukemia, chronic lymphocytic leukemia, multiple myeloma, and B cell lymphoma. With the deep research on EGR1, its expression, function and regulatory mechanism has been gradually elucidated, and provides more possibilities for treatment strategies of patients with leukemia. Herein, we summarize the roles of EGR1 in its biological function and relationship with leukemia.

Diagnostic utility of multiprobe fluorescence in situ hybridization assay for detecting cytogenetic aberrations in acute leukemia

BACKGROUND

Specific cytogenetic aberrations detected by conventional karyotyping or FISH play a major role in the diagnosis, prognosis, and treatment of patients with acute leukemia. The FISH technique enhances the capacity of conventional karyotyping to detect subtle chromosomal aberrations. Multiprobe FISH assay (Cytocell, UK) can hybridize multiple probes to a single slide, thereby increasing the detection rate of cytogenetic aberrations. This study aimed to evaluate multiprobe FISH in detecting cytogenetic abnormalities in acute leukemia.

METHODS

Thirty newly diagnosed acute leukemia patients who attended the hematology clinic at Dong-A University Hospital from October 2008 to October 2012 were enrolled in the study. The multiprobe FISH results were compared with those of G-banding.

RESULTS

Multiprobe FISH detected the chromosomal aberrations identified by G-banding, as well as additional aberrations in 6 of 30 (20.0%) cases, which included ETV6/RUNX1 translocation, p16 deletion, TP53 deletion, and IGH break-apart.

CONCLUSIONS

The multiprobe FISH assay was a more sensitive and reliable technique compared with G-banding. It was also more cost-effective and yielded faster results.

Molecular cytogenetic monitoring from CD34+ peripheral blood cells in myelodysplastic syndromes: first results from a prospective multicenter German diagnostic study

The gold standard of cytogenetic analysis in myelodysplastic syndromes (MDS) is conventional chromosome banding (CCB) analysis of bone marrow (BM) metaphases. Most aberrations can also be detected by fluorescence-in situ-hybridization (FISH). For this prospective multicenter German diagnostic study (www.clinicaltrials.gov: #NCT01355913) 360 patients, as yet, were followed up to 3 years by sequential FISH analyses of immunomagnetically enriched CD34+ peripheral blood (PB) cells using comprehensive FISH probe panels, resulting in a total number of 19,516 FISH analyses. We demonstrate that CD34+ PB FISH correlates significantly with CCB analysis and represents a feasible method for a reliable non-invasive cytogenetic monitoring from PB.