A Novel Technique for the Generation of Multitissue Blocks Using a Carrier.

Paraffin blocks containing several tissues have become a major tool in surgical pathology. As multitissue blocks, they usually consist of few rather large samples and as tissue microarrays (TMAs) they may contain up to several hundred small-sized tissue cores. We developed a novel approach to generate multitissue blocks using a carrier in which tissue samples are inserted. Normal tissues with homogenous consistency such as liver, spleen, and lung seem to be ideal carriers. Carrier tissue size can be freely chosen to accommodate number and size of sample tissues as desired. As the carrier tissue serves as a scaffold for the inserted tissue, even small-sized tissues will stay exactly as placed in the carrier. This makes carrier-based multitissue blocks (CBMTBs) an ideal approach when exact orientation of layers is important, for example in normal GIT tissues. The carrier tissue approach can also be used for few large-sized sample tissues or to generate classical TMAs with sample cores of <1 mm. As the newly generated CBMTB or carrier-based tissue microarray is completely reembedded after assembling, sectioning of CBMTBs is comparable with sectioning a normal solid tissue block producing virtually no sample loss and requiring minimal trimming and consequently vastly increasing yield.