Chapter 4 Discussion Questions and Answers

4.1 What is the purpose of tissue processing?

The purpose of tissue processing is to provide the tissue with a supportive medium to allow the preparation of thin tissue sections.

4.2 In what circumstances might frozen sections be of value?

Frozen sections may be of value in identifying if a lesion is malignant or not during the course of a surgical operation. If the margins of the sample submitted are clear of tumour then an operation may not take any further tissue. In a different case, if the frozen section shows tumour then an operation may not proceed as the tumour may have been identified as being too extensive to operate.

4.3 What section thicknesses are used in microtomy? Why?

Most routine tissue sections are cut at one cell thick which is about 3–4 µm thick. This allows a clear view of the cellular components of the tissue. Very cellular samples are cut thinner. Where amyloid is queried then sections are cut thicker at about 6–8 µm, which allows more of the amyloid to be stained. Neuropathology samples are cut thicker at 8–10 µm to allow the investigation of the flow of nerves through the tissue.

4.4 Why are internal quality control steps of value?

Internal quality control samples allow the standard of laboratory testing to be evaluated. This may start with checking that the patient details are correct, to whether the batches of reagents used are working appropriately. Internal quality control is about not assuming that the testing will be perfect but auditing the process to ensure that standards of work are maintained.