The construction of high-density paraffin tissue microarrays with 0.43-mm-diameter paraffin tissue core biopsies is technically feasible.

Paraffin tissue microarrays (PTMAs) are blocks of paraffin containing up to 1,000 paraffin tissue core biopsies (PTCBs). The growing number of publications in recent years bears eloquent witness to the advantages of these PTMAs in high-throughput molecular profiling of tumor specimens. In order to conserve the often minute quantities of available tumor tissue with precisely recorded follow-up data and to store the greatest possible number of PTCBs in one block, researchers often try to reduce PTCBs to the smallest possible diameter. Until now, the smallest feasible diameter for PTCBs was 0.6 mm. Experiments with diameters below 0.6 mm have failed due to the instability of the paraffin tissue punch. The process described allows the construction of PTMAs with PTCBs only 0.43 mm in diameter utilizing simple, inexpensive, self-made paraffin tissue punches and predrilled recipient blocks.