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Malignancy - solid tumour

Sample requirements

  • Paraffin embedded tumour tissue (4 micron) sections on poly-l-lysine coated slides (2 slides per FISH test required) with H&E slide

  • Unless sections comprise all tumour tissue (please indicate if all tissue is representative and an indication of tumour load) please ring the abnormal area on the reverse of slides to allow targeting of analysis. Sections with a tumour load <10% have an increased risk of a false-negative result; see limitations of tests below.

Full clinical information including suspected or confirmed diagnosis and tumour load are required for the accurate interpretation of the cytogenetic result.

For sample labelling and completion of referral form criteria please see referral requirements.


Acceptance and rejection criteria

If known upon receipt, PET slides will be rejected if there is insufficient material to process on the slides. Please see below for further information on limitations of PET FISH studies.


Tests available

We have a large number of FISH probes available in line with the test directory published on the NHS England website. Please see our Tumour FISH probe list. We are able to FISH preparations from paraffin embedded/frozen tissue. Please contact the Cytogenetics Department to discuss your requirements and the availability of FISH probes.

FISH image 1

FISH on paraffin embedded tissue sections. Positive MDM2 amplification.

FISH image 2

FISH on paraffin embedded tissue sections. Positive EWSR1 rearrangement.

FISH image 3

FISH on paraffin embedded tissue sections. Positive ALK rearrangement.

Reporting times

Please see our Target Reporting Times. To see our current TAT data; please see - Service turnaround times - East Genomics.

Limitations of tests

The success and accuracy of FISH studies on paraffin embedded tissue slides depends on the tumour load within the tissue on the slides and the amount of tissue itself. Generally at least 100 good quality interphase cells are analysed. A slide with a very small amount of tissue may therefore not be sufficient to obtain a full result. If the tumour load is low, the neoplastic clone may not be represented within the cells analysed. If the tissue has been damaged or crushed during the preservation process this may also compromise the result.

In addition please see our samples limitations page.

Storage and further testing

Paraffin embedded tissue slides (after FISH testing) are stored for 2 years. Any spare/unused paraffin embedded tissue slides are kept for 4 months from receipt and are either returned to the referring centre or discarded, depending on the request of the centre. All H+E slides are returned to the referring centres usually 4 months after receipt. Subsequent genetic testing can be requested at any time within this period but may not be possible depending on the quality of the material available.

Page last updated 21/02/2024. Please note that if printed, the information is only valid on the day of printing.