Tissue Microarray Advanced Techniques for Sampling Donor Blocks with Limited Tissue: The “Radical Tissue Microarray”
Thom Jensen, Dylan V Miller, David Nilson, Melissa Cessna. Intermountain Healthcare, Salt Lake City, UT
Background: Tissue Microarrays (TMAs) are increasingly used in pathology; economizing reagents, space, and interpretive time. High quality tissue arrays depend on donor blocks with adequate tissue. We report the use of advanced techniques that can be used to salvage tissue for TMA construction from blocks with limited tissue.
Design: We have developed strategies to maximize the yield of tissues from donor blocks in TMA construction. Two such techniques are outlined and illustrated according the nature of the sample limitation.
Results: Scraping Technique: Small tissue (e.g. needle biopsies) or tissie scattered throughout the donor block can be collected for TMA construction using the scraping technique. Using a marked H&E slide as a roadmap, tissue can be scraped from the donor block using a scalpel tip. The tissue scrapings can be carefully transferred to a skin biopsy punch whose diameter has been matched to permit the stylet from another TMA coring device (e.g. a 2mm skin punch with a 2mm stylet). The haphazard tissue scrapings are tamped down into the skin biopsy punch using the stylet and the resulting tissue "sausage" embedded in paraffin. Larger bore "sausages" can be sampled multiply by smaller bore coring devices (see figure). Perpendicular Stacking Technique: Tissue form nearly exhausted blocks (large surface area but shallow depth) can also be collected for TMA construction using the perpendicular stacking method. The paraffin block is melted and the remaining tissue wafer cut into several ∼0.5 cm squares. The squares are stacked then the stack turned on end and embedded. Cores can then be punched from vertically stacked tissue for use in TMAs (see figure). Because the TMA cores resulting from these techniques are slightly more fragile than solid tissue cores, It is recommended that the TMA coring device be used to punch a piece of thin cardboard just prior to coring a scraped or stacked tissue specimen. This will allow the cardboard to act as a barrier, protecting the tissue from indentation by the stylet.
Conclusions: Though limitations in donor tissue blocks present a challenge to high quality TMA construction, the scraping and perpendicular stacking techniques can be employed to increase the yield from limited blocks.
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 276, Wednesday Morning