Lymphoma associated chromosomal abnormalities can easily be detected by FISH on tissue imprints. An underused diagnostic alternative

Reliable cell and tissue morphology-based diagnosis of endemic Burkitt lymphoma in resource-constrained settings in Ghana

BACKGROUND

Endemic Burkitt lymphoma (eBL) is an aggressive B-cell lymphoma, which is a common childhood cancer in areas with intense transmission of Plasmodium falciparum parasites. Early and accurate diagnosis is a prerequisite for successful therapy, but it optimally involves advanced laboratory investigations. These are technologically demanding, expensive, and often difficult to implement in settings where eBL is prevalent. Diagnosis is thus generally based on clinical assessment and morphological examination of tumour biopsies or fine-needle aspirates (FNAs).

METHODS

The purpose of the present study was to assess the accuracy of eBL diagnosis at two tertiary hospitals in Ghana. To that end, we studied FNAs from 29 eBL patients and 21 non-eBL lymphoma patients originally diagnosed in 2018. In addition, we examined 111 archival formalin-fixed and paraffin-embedded (FFPE) biopsies from Ghanaian patients originally diagnosed as eBL (N = 55) or non-eBL (N = 56) between 2010 and 2017. Availability-based subsets of samples were subjected to haematoxylin-eosin or Giemsa staining, C-MYC immunohistochemistry, and fluorescence in situ hybridisation (FISH) analysis of c-myc rearrangements.

RESULTS

We found a good correlation between original diagnosis and subsequent retrospective assessment, particularly for FNA samples. However, evidence of intact c-myc genes and normal C-MYC expression in samples from some patients originally diagnosed as eBL indicates that morphological assessment alone can lead to eBL over-diagnosis in our study area. In addition, several FFPE samples could not be assessed retrospectively, due to poor sample quality. Therefore, the simpler FNA method of obtaining tumour material is preferable, particularly when careful processing of biopsy specimens cannot be guaranteed.

CONCLUSION

We conclude that the accuracy of eBL diagnostic tools available in Ghana is generally adequate, but could be improved by implementation of additional pathology laboratory investigations. Improved attention to adequate preservation of archival samples is recommended.

Detection of 14q32 rearrangements in multiple myeloma, using simultaneous FISH analysis combined with immunofluorescence

BACKGROUND

14q32 rearrangement has been identified as a recurrent hotspot of translocations in multiple myeloma (MM). The Fluorescence Immunophenotyping and Interphase Cytogenetics as a tool for the Investigation of Neoplasms (known as FICTION technique) for evaluation of chromosomal changes in MM. The aim of this work is to detect 14q32 rearrangement, using FICTION technique, on archival bone marrow (BM) slides of MM patients, and to study its prognostic value.

METHOD

This study was conducted at Ain Shams University Hospital. The FICTION technique, which uses CD138 and dual color, and the break-apart 14q32 rearrangement probe, was performed on archived smears of BM slides for 50 MM patients at the time of diagnosis.

RESULTS

A significantly higher percentage of cases were positive for 14q32 rearrangement by FICTION (32%) compared to fluorescence in situ hybridization (FISH) (12%) (p=0.04). Cases positive by FICTION for the rearrangement were designated as Group A, while negative cases were designated as Group B. Significantly lower Hb and CRP levels were found among Group B when compared to Group A patients (p=0.001 and 0.01, respectively). Serum albumin level and Bence Jones protein (BJP) significantly affect overall survival (OS) (p=0.01, 0.007, respectively). However, a statistically non-significant shorter mean survival time was found in positive cases through FICTION versus negative cases.

CONCLUSION

FICTION technique provides a sensitive tool for establishing clonal plasma cells (PC) infiltration of BM aspirates, and is amenable for use on archived as well as fresh smears.

Improved demonstration of immunohistochemical prognostic markers for survival in follicular lymphoma cells

Follicular lymphoma (FL) is one of the most common forms of the low-grade non-Hodgkin's lymphoma in adults, with a characteristic translocation, t(14;18)(q32;q21) that deregulates the expression of the BCL2 gene. The clinical course of FL patients is variable, whereby a subset of patients survive for long periods even without relapses, whereas the majority have frequent relapses with shorter survival. We have analyzed a series of 186 FLs, studying the correlation between clinical outcome and the tumor cell expression of a set of immunohistochemical markers, using an automated procedure for tissue microarrays to reduce the subjectivity of scoring. The results identified several markers associated with differences in overall survival (OS) in univariate analyses, such as Cyclin E, Mdm2, CD10, p21, IgD, Bcl-xL, CD30, and E2F6. Cases with a higher level of expression of Cyclin E, Mdm2, p21, IgD, Bcl-xL, CD30, and E2F6 were associated with a significantly shorter OS. On the other hand, strong CD10 expression was linked to a significantly better outcome. A Cox model was then constructed, integrating the Follicular Lymphoma International Prognostic Index (FLIPI) score and a restricted selection of three immunohistochemical markers: Cyclin E, Mdm2, and CD10 expression. A potentially useful finding is that the integrated FLIPI plus immunohistochemical model can be used to identify a subset of 26 patients (almost 20% of the total series), with a survival probability of 100% at 5 years. This not only confirms that a group of FL cases may have a very good clinical course, but also indicates that this group can be identified using this integrated clinical and immunohistochemical approach.

Fluorescent in situ hybridization heating pretreatment: the key is temperature control

Fluorescent in situ hybridization (FISH) is a very useful tool for diagnostic and prognostic purposes in pathology. However, many laboratories still experience troubles when applying FISH to paraffin material. To overcome these difficulties, different pretreatments which include enzymatic digestion have been described. Usually, previous to digestion, a heating step is performed. The aim of this study was to compare the efficiency of the heating step with different buffers and different heating methods. We conclude that the main factor in the heating pretreatment is the temperature control, irrespective of the buffer used. Best results are obtained with any buffer by heating the slides to 99°C for 15 min followed by 10 min at room temperature.

Simultaneous phenotyping and genotyping (FICTION-methodology) on paraffin sections and cytologic specimens: a comparison of 2 different protocols

Combining immunofluorescence labeling with fluorescence in situ hybridization (FISH) is a powerful technique simultaneously studying immunophenotypic markers and genetic abnormalities present in tumor cells [the FICTION method (fluorescence immunophenotyping, and interphase cytogenetics as a tool for the investigation of neoplasms)]. However, few studies have been applied to the technical problems posed by antigen retrieval and accessibility of genetic probes to target-DNA, using formalin-fixed, paraffin-embedded tissue. In this study, we compared 2 immunofluorescence detection systems, the 3-step IF (TIF) method against the Tyramide Signal Amplification techniques (TSA). The FICTION-TSA technique significantly improved the sensitivity for detection of the immunophenotypic markers without influencing specific probe hybridization to target-DNA, compared with the results obtained with the TIF method. The reaction product of the TSA system was robust to the following FISH procedure in contrast to the TIF technique. The TSA technique used also allowed synchronous detection of nuclear antigens and FISH signals using both fusion (IgH/CCND1) and break-apart (CCND1) probes on formalin-fixed paraffin-embedded tissue.

Investigation of bone marrow involvement in malignant lymphoma using fluorescence in situ hybridization: possible utility in the detection of micrometastasis

We evaluated the usefulness of interphase fluorescence in situ hybridization (FISH) for the detection of bone marrow involvement of lymphoma, comparing the results with those of microscopic examination. Bone marrow aspirates obtained for staging work-up from 150 patients with non-Hodgkin lymphoma were used in this study. Interphase FISH study using four probes and conventional G-banding were performed on bone marrow aspirates. The four probes included locus specific identifier (LSI) immunoglobulin heavy chain (IGH) dual-color break-apart rearrangement probe, an LSI p16 SpectrumOrange/CEP 9 SpectrumGreen probe, an LSI BCL6 dual-color break-apart rearrangement probe. Among 150 cases, 29 cases (19.3%) showed infiltration of neoplastic lymphoid cells by microscopic examination. Chromosomal aberrations were detected by FISH in eight patients and by conventional cytogenetic study in three patients. FISH study showed 14q32 rearrangement in four patients (4/126, 3.2%), 9q21 rearrangement in no patients (0/144, 0%), 3q27 rearrangement in four patients (4/131. 3.1%), and a gain of 1q21q32 in two patients (2/115, 1.7%). Among eight patients with abnormal FISH patterns, six had normal karyotypes or no analyzable metaphase according to the conventional cytogenetic study. Seven patients with FISH abnormality showed bone marrow involvement of lymphoma by microscopic examination. One patient, who was defined as having no evidence of bone marrow involvement by microscopic examination, showed a 3q27 aberration in the FISH study. Although the number of patients with BM involvement that was detected by FISH was low, abnormal FISH patterns were detected in six patients who did not have abnormal karyotypes. Therefore, FISH analysis would be beneficial in cytogenetic diagnosis and follow-up study of minimal residual diseases, once the cytogenetic changes are detected at initial diagnosis.