Mega Blocks Scheme

The Mega Blocks Scheme utilises both the paraffin wax embedded block and its corresponding haematoxylin and eosin (H&E) stained slide, both of which play a critical role in tissue-based diagnosis.

Stains assessed:

Selected / In-house Material (all assessment runs)

Paraffin wax embedded tissue block

Haematoxylin and eosin (H&E)

Specimen types:

Specific specimen types are not requested, and Participants’ are permitted to submit any specimen type, as long as the specimen type is representative of a Participants’ in house repertoire.

Conventional Cellular Pathology tissue selection uses standard sized tissue cassettes and taking multiple sections of tumour tissue; however tumours can consist of heterogeneous changes therefore they can differ at different sites. This intra-tumour heterogeneity has lead to the use of large cassettes, or Mega Blocks. These large cassettes can contain ten times the volume of a standard sized cassette and provide a more efficient way of assessing large areas of tissue thus reducing the risk of “under-sampling”.

The role of external quality assessment and proficiency testing is essential in order to provide assurance that a high standard of testing is achieved for all. Errors with tests can have catastrophic results so it is important for UK NEQAS CPT to ensure early detection of problems and provide education, help and support to organisations.