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PubMed1994

[A standardized AgNOR stain method for formalin fixed and paraffin embedded material].

Visualization of proteins associated with nucleolar organizer regions proteins (AgNORs) on formalin-fixed and paraffin-embedded archival tissues is substantially improved after application of wet autoclave pretreatment. Silver staining results are comparable to those obtained on tissues processed in alcohol based fixatives, illustrating AgNORs as substructures of the nucleoli without any staining artefacts. A highly reproducible staining quality was achieved irrespective of tissue origin or duration of formalin fixation. As a result of this novel and simple method, the grounds have been prepared for standardized AgNOR quantification on archival material.

Fixatives↗

PubMed2004

Application of in situ hybridization probes for MLH-1 and MSH-2 in tissue microarrays of paraffin-embedded malignant melanomas: correlation with immunohistochemistry and tumor stage.

Defects in DNA mismatch-repair genes MLH1 and MSH2 reported primarily in hereditary nonpolyposis colorectal carcinoma are present in many sporadic tumors, including malignant melanomas. The main aim of this study was to investigate the expression of these genes in malignant melanomas in relation to tumor stage. An experiment was performed on paraffin-embedded tissue microarrays of malignant melanomas applying in situ hybridization with probes produced by our research group and immunohistochemical techniques. In situ hybridization demonstrated MLH1 expression in 45 of 59 melanomas and MSH2 expression in 51 of 59 melanomas. Immunohistochemistry detected MLH1 expression in 46 of 59 melanomas and MSH2 expression in 50 of 59 melanomas. Down-regulation of expression of both DNA mismatch repair genes in malignant melanomas was observed. The findings obtained by in situ hybridization and immunohistochemistry correlated significantly. Our study demonstrates the suitability of in situ hybridization with MLH1 and MSH2 probes for paraffin-embedded tissue. Tissue microarrays can be used successfully in both in situ hybridization and immunohistochemistry to analyze the expression of DNA mismatch-repair genes.

Adaptor Proteins, Signal Transducing↗

PubMed1993

DNA flow cytometry from paraffin-embedded tissue in diagnosis of cutaneous malignant lymphomas and pseudolymphomas.

DNA content and cell cycle distributions in paraffin-embedded blocks of 111 skin biopsy specimens of 70 patients with cutaneous malignant lymphomas (CML) and 41 patients with cutaneous pseudolymphomas (CPL) including chronic actinic dermatitis (CAD) were estimated by DNA flow cytometry. A statistical significant difference between DNA indices (DIs) or proliferative indices (PIs) for CML including mycosis fungoides (MF) II, MF III, Sezary's syndrome (SS), cutaneous peripheral T-cell lymphomas other than MF and SS, cutaneous germinal center cell-derived lymphomas and cutaneous genuine histiocytic lymphoma from CPL. DIs were also helpful in differentiating MF I from CPL. There was a linear relationship between DIs and PIs, both of which had a parallel relationship to the degrees of malignancy and mortality of varieties of CML. The finding of aneuploidy is likely to be useful in differentiating CML from CPL. It is worth noting that DIs, PIs and proportions of aneuploidy in CAD were all higher than those of higher malignancy of CML. These data could not be considered as markers of malignancy.

Adolescent↗

PubMed1997

Allelic loss detected on chromosomes 8, 10, and 17 by fluorescence in situ hybridization using single-copy P1 probes on isolated nuclei from paraffin-embedded prostate tumors.

We have implemented a reliable new technique for preparing isolated prostate cancer nuclei from paraffin-embedded tissue sections followed by analysis with single-copy fluorescence in situ hybridization (FISH). Our initial validation is described by comparison of our data with fresh prostate tumor tissue and loss of heterozygosity (LOH) studies. We also describe evaluation of 36 previously unstudied prostate cancer patients. Fifteen archival samples were selected from patients who underwent radical prostatectomy in which direct FISH and LOH data were available. Isolated nuclei were prepared and allelic loss was detected on 17q using a single-copy DNA (P1 phage) probe by FISH. A high (80%) concordance was found when comparing isolated nuclei data with 17q results from fresh preparations and LOH studies. We also examined loss at sites on 8p, 10q, and 17q in samples from 36 patients for whom clinical information was available. Loss was found at any of the three loci in 32/36 (89%) of the specimens with specific loss in 53% of the cases at the 8p locus, 33% at the 10q locus, and 61% at the 17q locus. Studies indicate that, as well as providing potential clinical information, isolated nuclei preparations are as reliable as fresh tissue for single-copy FISH studies.

Aged↗

PubMed2026

Determinants of nucleic acid quality in formalin-fixed paraffin-embedded bladder urothelial carcinoma specimens: effects of specimen type, fixation conditions, and storage time.

Formalin-fixed paraffin-embedded (FFPE) tissue is the principal substrate for cancer genomic profiling, yet pre-analytical factors affect nucleic acid quality. In our workflow, transurethral resection (TUR) specimens of bladder urothelial carcinoma are fixed promptly but exposed to electrocautery, whereas robot-assisted radical cystectomy specimens are refrigerated overnight before fixation; we compared nucleic acid quality between these specimen types. We analyzed 56 FFPE primary bladder urothelial carcinoma specimens (33 TUR, 23 cystectomy). DNA quality was assessed by the DNA Integrity Number (DIN) and short-to-long cycle threshold ratio (S/L Ct ratio), and RNA quality by the RNA Integrity Number (RIN) and percentage of RNA fragments ≥200 nucleotides (DV200), with group comparisons, Spearman correlations, and multivariable regression (specimen type, fixation duration, storage time). The median DIN (4.4 vs. 3.8, p = 0.004) and S/L Ct ratio (0.943 vs. 0.894, p < 0.001) were higher in TUR than cystectomy specimens; the RIN was also higher (1.9 vs. 1.7, p = 0.040), though low in both groups, and DV200 did not differ (50.3% vs. 47.7%, p = 0.934). In multivariable analysis, TUR specimen type independently predicted higher DIN (β = +0.460, p = 0.040) and S/L Ct ratio (β = +0.442, p = 0.009), whereas longer storage time independently decreased the S/L Ct ratio (β = -0.513, p < 0.001) and RIN (β = -0.352, p = 0.010). In our institutional workflow, TUR specimens showed higher DNA quality metrics than robot-assisted radical cystectomy specimens subjected to overnight refrigerated pre-fixation delay, whereas this workflow-associated advantage did not clearly extend to DV200-defined RNA fragment-length quality. Storage time was associated with selected aspects of nucleic acid deterioration.

Humans↗

PubMedDate not supplied

Comparison of polymerase chain reaction and catalyzed signal amplification in situ hybridization methods for human papillomavirus detection in paraffin-embedded cervical preneoplastic and neoplastic lesions.

BACKGROUND: Two molecular methods for HPV genotyping in formalin-fixed, paraffin-embedded tissue were evaluated: in house polymerase chain reaction assay (PCR) with consensus and type-specific primers and a novel procedure of in situ hybridization-a catalyzed signal amplification system (CSA-ISH, Genpoint, DAKO, Glostrup, Denmark). The number of HPV positive cases and detected viral types were compared in cervical biopsies and cone specimens according to histopathological diagnosis. Primer efficiency in detecting various types of HPV by PCR method was evaluated. METHODS: DNA samples (101) were used as a template to amplify with three pairs of consensus (MY09/11, GP5+/6 +, CPI/IIG) and four type-specific HPV primers (HPV-6/11, 18, 16 and 33). The according histological tissue sections were analyzed with CSA-ISH method, using commercial HPV biotinylated probes HPV-6/11, 16/18 and 31/33/51. RESULTS: The degree of concordance for PCR and CSA-ISH was 64.4%. In 63 of 101 samples (62.4%), HPV was detected by PCR, while only 35 (34.7%) were positive using CSA-ISH. CSA-ISH found lower percentages for all HPV types, except HPV-6/11. A lower percentage of positive results in all high-grade lesions was detected by CSA-ISH. Multiple infections were detected by PCR in only one sample and in three samples by CSA-ISH. Detection with My09/11 primers followed by Gp5+/6+ primers, in nested reaction, gave the highest number of positive results: 58 of 63 (92%). None of the samples diagnosed as condylomata planum or CIN I was positive for HPV-6/11 (low risk type), which was detected exclusively in condylomata acuminatum group. CONCLUSIONS: A significantly higher number of positive samples was detected with PCR than with CSA-ISH method. CSA-ISH method should be improved, especially in detecting HPV in high-grade lesions. CSA-ISH may be more accurate in detection of multiple infections. GP5+/6+ in nested reaction after MY09/11 detected the highest number of positive results. Samples diagnosed as benign lesions positive on HPV-X must be monitored as possible candidates for progression. CIN I lesions, which were HPV negative, probably will not progress. This finding may be important in planning therapy and avoiding unnecessary treatment.

Biopsy↗

PubMed1994

Demonstration of mitochondrial ribosomal RNA in frozen and paraffin-embedded sections of skeletal muscle by in situ hybridization.

We have used in situ hybridization with synthetic oligonucleotide probes to the 16S sub-unit of mitochondrial ribosomal RNA to detect mitochondrial accumulations in biopsies of skeletal muscle from 16 patients with mitochondrial myopathies. In all cases, the distribution of the hybridization signal matched the pattern of succinate dehydrogenase activity in adjacent cryostat sections. In situ hybridization also allowed visualization of mitochondrial accumulations in paraffin-embedded sections of skeletal muscle that had been fixed in either De Castro's solution or formalin. DNase pre-treatment did not significantly diminish the intensity of hybridization signal, suggesting that the hybridization is predominantly to RNA. The advantages of this technique are that it allows the investigation of mitochondrial disorders when only paraffin-embedded tissue is available and should also facilitate the demonstration of mitochondrial accumulations in tissues other than skeletal muscle.

Biopsy↗

PubMed1991

DNA ploidy of malignant melanoma determined by image cytometry of fresh frozen and paraffin-embedded tissue.

Image analysis of DNA content was performed from single nuclei of melanoma monolayer imprints made from fresh frozen tissue of 14 patients with primary malignant melanoma and 16 patients with local recurrences at the incision site and local or distant metastases. This procedure requires fewer cells and is an advantage when the quantity of tumor available is limited, especially in thin low Breslow depth cutaneous melanomas. Image analysis allowed reproducible measurement of DNA ploidy from 100 cells. The frequency of aneuploidy was similar in primary and metastatic melanomas. Three of 3 patients with euploid primary melanomas showed no evidence of recurrences or metastases, though one died of unrelated disease with short follow-up. The 4 patients with primary melanoma who developed metastases had aneuploid primaries; two of these patients died of metastatic disease. Three of 4 patients with euploid metastatic tumors were free of disease at last follow-up, and 1 patient died with stable disease. Nine of 12 patients with aneuploid tumors died of metastatic disease. The frequency of DNA ploidy in the present image analysis study correlated with previous flow cytometry studies. In 9 patients with primary tumors with a Breslow depth greater than 0.75 mm, the DNA content was also determined in nuclei obtained from formalin-fixed paraffin-embedded tissue. The frequency of aneuploidy was higher in fresh tissue (7 of 9) as compared with paraffin-embedded tissue of the same cases (4 of 9).

Aneuploidy↗

PubMed1994

Demonstration of URR-duplication variants of human papillomavirus type 6 in paraffin-embedded tissue sections of one condyloma acuminatum and one Buschke-Loewenstein tumour.

Human papillomavirus type 6 (HPV 6) induces condylomata acuminata and laryngeal papillomas. Occasionally, HPV 6 may also be found in low-grade verrucous carcinomas. In some tumours, genetic analysis revealed the presence of HPV 6 variants with rearrangements, mostly DNA duplications, within the upstream regulatory region (URR). In this study, we analysed 98 formalin-fixed, paraffin-embedded condylomata acuminata obtained from 54 patients for the presence of URR-duplication variants of HPV 6. HPV 6 DNA could be amplified by polymerase chain reaction (PCR) from 40 samples. One condyloma acuminatum contained a HPV 6 genome with rearranged URR. Analysis using restriction enzyme cleavage suggested a DNA duplication within the URR of approximately 200 bp, spanning the Hpa II site at nt 7863 and the Dde I site at nt 7843 but not involving the Rsa I site at nt 7633. In addition, we analysed the distribution of the already characterized URR-duplication variant HPV 6AC1B within different paraffin-embedded tissue sections of a Buschke-Loewenstein tumour. No correlation could be demonstrated between the presence of the rearranged genome and malignant histological changes. This result and the demonstration of an URR-duplication variant in a typical condyloma acuminatum suggest that duplications within the URR of HPV 6 are not directly related to malignant progression of HPV 6-induced tumours.

Base Sequence↗

PubMed2005

Improved diagnosis of mycobacterial infections in formalin-fixed and paraffin-embedded sections with nested polymerase chain reaction.

Traditional histological diagnosis of mycobacterial infection in formalin-fixed and paraffin-embedded (FFPE) tissues is insensitive and poorly specific. To improve this, we developed nested polymerase chain reaction (PCR) protocols for detecting a Mycobacterium genus-specific 65-kDa heat shock protein (HSP65) sequence and the M. tuberculosis complex-specific insertion sequence IS6110 in FFPE sections. Protocols were optimized on tissues from 20 patients with a final clinical diagnosis of mycobacterial infection. Amplicons were controlled by sequencing and restriction endonuclease digestion. PCR could detect as few as three mycobacterial genomes per reaction. Assays showed 100% sensitivity and specificity for both M. tuberculosis complex and M. avium complex infection. Paraffin blocks from a second group of 26 patients with histological evidence of necrotizing granulomas of unknown etiology were then analyzed as a surrogate group to test the assay under conditions similar to those applying during routine diagnosis. Twenty-three of these blocks contained amplifiable DNA; nine were positive for M. tuberculosis complex DNA and four for other types of mycobacterial DNA. Furthermore, digestion of HSP65 amplicons with NarI could distinguish M. tuberculosis from M. avium complex. In conclusion, our nested PCR assays can be used as reliable tools for the detection of mycobacterial infections in FFPE tissues. The assays are simple and rapid to perform and show improved sensitivity and specificity compared to previously reported protocols.

DNA, Bacterial↗

PubMed1997

Interphase cytogenetic analysis of myxoid soft tissue tumors by fluorescence in situ hybridization and DNA flow cytometry using paraffin-embedded tissue.

BACKGROUND: Myxoid liposarcoma is one of the major myxoid malignancies of soft tissue and its histologic differentiation from other myxoid tumors is sometimes difficult. Recent cytogenetic analysis revealed that a characteristic reciprocal chromosomal translocation of t(12;16)(q13;p11) occurs in myxoid liposarcomas. In this study, retrospective cytogenetic analysis by means of fluorescence in situ hybridization (FISH) and DNA flow cytometry were performed on free nuclei isolated from paraffin embedded myxoid liposarcoma cells, and they were compared with myxoid malignant fibrous histiocytomas (MFHs), low grade fibromyxoid sarcomas, and intramuscular myxomas. METHODS: Nine myxoid liposarcomas, five myxoid MFHs, two low grade fibromyxoid sarcomas, and four intramuscular myxomas were examined. Chromosomal aberrations in chromosomes 12 and 16 were investigated by FISH, using both centromeric DNA probes and whole chromosome painting probes. Cellular DNA contents were determined by flow cytometry. RESULTS: All nine myxoid liposarcomas were shown to be diploid by DNA flow cytometry and exhibited the translocation t(12; 16), as shown by FISH. Four of the five myxoid MFHs exhibited aneuploidy, as shown by flow cytometry, and remarkable numeric aberrations of chromosomes 12 and 16. No abnormal DNA content or chromosomal aberrations were identified in the two low grade fibromyxoid sarcomas or the four intramuscular myxomas. CONCLUSIONS: FISH analysis performed on paraffin embedded materials can be used to differentiate myxoid liposarcomas from other myxoid soft tissue tumors.

Adult↗

PubMed1997

Comparative FISH analysis of numerical chromosome 7 abnormalities in 5-micron and 15-micron paraffin-embedded tissue sections from prostatic carcinoma.

Interphase fluorescence in situ hybridization (FISH) was performed on 15-micron-thick paraffin sections from prostatic carcinomas using a chromosome 7-specific alpha-satellite DNA probe. A confocal laser scanning microscope (CLSM) was used for optical sectioning of the thick sections and reconstruction of 3D images. The number of FISH signals was determined by a gallery of optical sections evaluating only complete nuclei. To investiate the influence of section thickness and truncation and nuclei on scoring results, we compared the FISH data from 15-micron sections with signal counts obtained from 5-micron sections. The latter were evaluated by conventional fluorescence microscopy in the same tumor regions previously defined and marked on the slides. After statistical analysis of spot frequencies in tumor and non-tumorous cells (chi 2 test), we transferred the signal frequencies into a cytogenetic classification (-7, +7, polysomy 7). Based on this classification, most cases showed more than one chromosome 7 aberration type. Trisomy 7 (+7) became apparent in 15-micron thick sections in all 19 tumors, polysomy 7 (> 3 spots) in 18/19 cases, and monosomy 7 (-7) in 13/19 cases. In 5-micron sections, however, trisomy 7 and polysomy 7 were found in only 7/19 and 13/19 cases, respectively, and monosomy 7 in 7/19 cases. When comparing the classification results of tumor cells of the same tumor regions originating either from 5-micron or 15-micron sections, the following discrepancies were noted: in 15-micron sections exclusively, in 12/19 tumors, trisomy 7 was found; in 6/19 cases, polysomy 7; in 8/19 cases, monosomy 7. The high proportion of cases with tumor nuclei expressing only one hybridization signal of chromosome 7 in 15-micron sections could be confirmed as monosomy 7 in five selected cases by double-hybridization using centromere-specific probes for chromosomes 7 and 12. These results demonstrate that numerical chromosome 7 aberrations are more frequently observed in thick (15-micron) paraffin-embedded tissue sections by evaluating only complete nuclei. The use of routine sections (5-micron) for interphase cytogenetic analyses is compromised by a remarkable underestimation of the real chromosome copy numbers.

Adenocarcinoma↗

PubMed1982

A simplified Timm stain procedure compatible with formaldehyde fixation and routine paraffin embedding of rat brain.

A simplified sulphide/silver technique for visualizing transitional metals in rat brain is described. It consists of: (1) sulphide perfusion before formaldehyde perfusion, (2) routine paraffin embedding and sectioning, and (3) silver staining with physical developer. This method is compatible with formaldehyde fixation, eliminates the need for post-fixation in Carnoy's solution before embedding and does not require low paraffin temperatures during embedding. Once embedded, brains can be stored for months before sectioning without loss of stain quality.

Animals↗

PubMed1990

HLA-A- and HLA-B-specific monoclonal antibodies reactive with free heavy chains in western blots, in formalin-fixed, paraffin-embedded tissue sections and in cryo-immuno-electron microscopy.

The mAb HCA2 reacts preferentially with HLA-A locus heavy chains. Its reactivity contrasts with that of HC10, a mAb with more pronounced specificity for HLA-B and -C heavy chains. Both HCA2 and HC10 were raised against free class I heavy chains of HLA-A and -B antigens respectively, to obtain mAbs that would still react with denatured class I antigens, as they occur in Western blotting, conventional light microscopical analysis of formalin-fixed, paraffin-embedded sections, and cryo-immuno-electron microscopy. HCA2 and HC10 indeed retain strong reactivity with free class I heavy chains in Western blots. The HCA2 mAb in particular reacts in a locus-specific manner by biochemical criteria. Conditions are described for use of HCA2 and HC10 in immunohistochemical staining of formalin-fixed, paraffin-embedded sections. HCA2 and HC10 also produce strong reactivity in immuno-electron microscopy. Their use allows the determination of tissue and subcellular distribution of class I antigens.

Antibodies, Monoclonal↗

PubMed1991

Growth fraction estimation of malignant lymphomas in formalin-fixed paraffin-embedded tissue using anti-PCNA/Cyclin 19A2. Correlation with Ki-67 labeling.

The immunohistochemical detection of PCNA/Cyclin, a nuclear protein associated with cell proliferation, represents a potentially useful tool for the study of tumor proliferative activity. Previous studies investigating the reactivity of anti-PCNA/Cyclin monoclonal antibody 19A2 have not clearly defined the population of proliferating cells with which 19A2 reacts in tissue sections. The authors describe a method for detection of PCNA/Cyclin in formalin-fixed, paraffin-embedded tissue using a routine biotin-streptavidin immunohistochemical system that employs an anti-IgM, mu-chain-specific second-stage antibody. The authors used this method to study the proliferative activity of 24 malignant lymphomas, consisting of 12 low-grade lymphomas (LGLs) and 12 intermediate-grade lymphomas (IGLs), and five reactive tonsils. 19A2 data was compared with Ki-67 labeling in frozen sections in the same group of cases. 19A2 provided easily detectable nuclear staining of proliferating cells with reactive cells demonstrating varying intensity of staining, this latter finding most likely due to the varying nuclear concentration of PCNA/Cyclin protein during the cell cycle. In tonsils, 19A2 reacted with germinal center cells and basal keratinocytes. In the malignant lymphomas, there was good correlation between 19A2 and Ki-67 data (r = 0.90, P less than 0.001). The subgroup of LGLs showed a mean PCNA/Cyclin of 26% and a mean Ki-67 of 28%. In the subgroup of IGLs, mean PCNA/Cyclin = 54% and mean Ki-67 = 59%. These results indicate that 19A2 detects a fraction of proliferating cells that is similar to that detected by Ki-67, ie, the growth fraction, and that 19A2 is a reliable marker of proliferative activity in uniformly handled, formalin-fixed, paraffin-embedded tissue.

Antibodies↗

PubMed2003

Rhodococcus equi and genetic susceptibility: assessing transferrin genotypes from paraffin-embedded tissues.

Rhodococcus equi is a bacterial pathogen, ubiquitous in the soil, that infects many foals and is lethal to some. Transferrin is an iron-binding protein that has bacteriostatic properties in the blood. Transferrin is also highly polymorphic in most species, with 15 variants identified for horses using biochemical methods, and may be responsible for variation in susceptibility to bacterial pathogens. The objectives of this study were 1) to compare biochemical typing with DNA typing of transferrin, 2) to determine if transferrin DNA from archival paraffin-embedded tissue samples can be recovered and typed with molecular methods, and 3) to determine if there was an association between foal death caused by R. equi and transferrin type. Comparing biochemical methods and DNA sequencing for 41 horses demonstrated correspondence between the typing methods. The allele frequency of archival paraffin-embedded tissue samples from 34 Thoroughbred foals that succumbed to R. equi showed an excess of the F allele and a deficiency of the D allele (P < 0.05). Year of collection (P > 0.8), age of foal (P > 0.3), and sex of foal (P > 0.6) were not statistically associated with transferrin type. The archival material was successfully transferrin typed using DNA sequencing, and there may be an association between foal death caused by R. equi and transferrin type.

Actinomycetales Infections↗

PubMed2002

[Investigation of practical application of fluorescence in situ hybridization (FISH) analysis using microwave irradiation in formalin-fixed, paraffin-embedded tissue sections].

We investigated fluorescence in situ hybridization (FISH) analysis using microwave irradiation in formalin-fixed, paraffin-embedded tissue sections of breast fibroadenoma. Higher percentage of cells with 2 signal copies of chromosome 3 centromere could be obtained in the condition of 5 microns thick sections, when we counted cells of more than 4 microns of nuclei in thickness. This method showed about the same results as FISH using cells separated from the same tissues. Percentage of cells with 2 signal copies of chromosome 17 centromere in 14 cases was 80.6 +/- 4.0% (Mean +/- S.D.). This method is expected in the application of the prognosis estimation of the breast cancer.

Breast Neoplasms↗

PubMed2001

Congenital-infantile fibrosarcoma. A clinicopathologic study of 10 cases and molecular detection of the ETV6-NTRK3 fusion transcripts using paraffin-embedded tissues.

Congenital-infantile fibrosarcoma (CIFS) is a relatively indolent sarcoma that should be distinguished from more aggressive spindle cell sarcomas of childhood. CIFSs have been found to have a novel recurrent reciprocal translocation t(12;15)(p13;q25) resulting in the gene fusion ETV6-NTRK3 (ETS variant gene 6; neurotrophic tyrosine kinase receptor type 3). We studied immunohistochemical expression of NTRK3, and conducted a reverse transcription-polymerase chain reaction (RT-PCR) assay to detect the ETV6-NTRK3 fusion transcripts using archival formalin-fixed paraffin-embedded tissues from 10 CIFSs. Thirty-eight other spindle cell tumors were included as controls. The ETV6-NTRK3 fusion transcripts were identified in 7 (70%) of 10 CIFSs. Nucleotide sequence analysis showed that the fusion occurred between ETV6 exon 5 and NTRK3 exon 13. The 38 control tumors were negative for the fusion transcript. Immunohistochemically, CIFSs consistently expressed NTRK3. But the expression of NTRK3 also was observed in 22 of 38 control tumors. These results show the diagnostic usefulness of RT-PCR methods to detect ETV6-NTRK3 fusion transcripts in archival formalin-fixed paraffin-embedded tissue and the important role of NTRK3 in the development of CIFS, despite its being a protein of little importance in differential diagnosis.

Child↗