Application of a novel and low cost technique to construct paraffin tissue microarrays out of paraffinised needle biopsy specimens from patients with breast cancer.

BACKGROUND: Paraffin tissue microarrays (TMAs) are a well accepted tool in pathology for high throughput molecular profiling, quality control and clinicopathological trials. No reports on TMAs constructed from paraffinised needle biopsy specimens (PNBSs) derived from patients with breast cancer can be found in the literature. PNBSs are sometimes the only source for tumour characterisation important for treatment. AIM: To develop a novel and low cost technique to construct TMAs from PNBSs (PNBSs-TMAs) in order to close this gap in TMA technology. METHODS: Using a skin biopsy punch, tumour-bearing parts of 84 PNBSs were punched out of the donor blocks, freed from the surrounding paraffin by melting and manually transferred into the preformed holes in the recipient block. After filling the holes, the PNBSs-TMA was fixed to a double sided adhesive tape and completely melted. Quality assessment of this new technique was performed comparing the HER2 status (synonym: cerbB2) of the PNBSs-TMA with the results of the original PNBSs and a TMA harbouring the tumour in corresponding resection and mastectomy specimens (RM-TMA). RESULTS: A 187-hole PNBSs-TMA with 84 PNBSs was successfully constructed. About 1% of the included PNBSs displayed signs of rolling and folding or of floating off the slide during the staining procedure. The results of immunohistochemistry, fluorescence in situ hybridisation and automated brightfield double in situ hybridisation showed high quality standard of the PNBSs-TMA, suitable for precise tumour profiling. CONCLUSIONS: PNBSs-TMAs are suitable for clinicopathological trials, especially those in which PNBSs are the only tumour source.

Paraffin tissue microarrays constructed with a cutting board and cutting board arrayer.

Paraffin tissue microarrays (PTMAs) are blocks of paraffin containing up to 1300 paraffin tissue core biopsies (PTCBs). Normally, these PTCBs are punched from routine paraffin tissue blocks, which contain tissues of differing thicknesses. Therefore, the PTCBs are of different lengths. In consequence, the sections of the deeper portions of the PTMA do not contain all of the desired PTCBs. To overcome this drawback, cutting boards were constructed from panels of plastic with a thickness of 4 mm. Holes were drilled into the plastic and filled completely with at least one PTCB per hole. After being trimmed to a uniform length of 4 mm, these PTCBs were pushed from the cutting board into corresponding holes in a recipient block by means of a plate with steel pins. Up to 1000 sections per PTMA were cut without any significant loss of PTCBs, thereby increasing the efficacy of the PTMA technique.

One-step complete melting of paraffin tissue microarrays using stabilization bodies.

Paraffin tissue microarrays (PTMAs) are constructed by putting paraffin tissue core biopsies (PTCBs) from donor blocks into the preformed holes of a recipient block. One problem that can occur during sectioning of a PTMA is that PTCBs can fold up. This may be caused by insufficient adhesion of the paraffins of the PTCBs and the recipient block. Mengel et al solved this problem by melting the PTMA block in a 2-step melting procedure. To simplify this melting procedure by reducing it to 1 step, we propose the use of paraffinized stabilization bodies, that is tissue or other biologic or synthetic material, for the construction of PTMAs. Because they keep their structure while the PTMA melts, they stabilize the PTCBs. Thus, a PTMA with a stabilization body can be fully melted in 1 step with a routine device like a hot plate without danger of the PTCBs toppling over.

Increasing the efficiency of paraffin tissue microarrays by packing the paraffin tissue core biopsies in a honeycomb pattern.

Paraffin tissue microarrays (PTMAs) are blocks of paraffin holding up to 1000 paraffin tissue core biopsies (PTCBs) for high throughput molecular analysis. The number of PTCBs in a PTMA depends on the surface area of the PTMA, the diameter of and the distance between the PTCBs and on their arrangement inside the assembled PTMA. The PTCBs are usually arranged in a rectangular x-y pattern of rows and columns. This design facilitates the construction of a PTMA because the operator simply turns the wheels of an x-y-table for a set, unchanging distance. The evaluation of the stained sections is also relatively easy. However, this rectangular arrangement means wasted space in the PTMA. To reclaim this space, the PTCBs could be arranged in a honeycomblike pattern. For every 8 rows in the conventional rectangular arrangement, 1 additional row of PTCBs can be packed. However, the researcher has to become accustomed to this uncommon arrangement when filling and evaluating the PTMA. Automatic slide readers and specially designed computer programs for the digital evaluation of the PTMAs can be helpful. In summary, the arrangement of PTCBs in a honeycomblike pattern increases the density and number of specimens stored in a PTMA, thereby enhancing its efficiency.

Depositing archived paraffin tissue core biopsy specimens in paraffin tissue microarrays using a paraffin tissue punch modified with a countersink.

Paraffin tissue microarrays (PTMAs) introduced by Kononen et al in 1998 have become a widely used technique in routine pathology and even more so in research. Kononen used a tissue puncher/arrayer (Beecher Instruments, Sun Prairie, WI, USA) to take paraffin tissue core biopsy specimens (PTCBs) of 0.6-2 mm in diameter from routine paraffin tissue blocks and transfer them to another paraffin block with up to 1000 holes. As pointed out by Mengel et al, however, it is not possible to use the Kononen/Beecher system to construct PTMAs out of archived PTCBs. To overcome this drawback in the extremely popular Beecher system, the paraffin tissue punch was modified by incorporating a conical 4 mm deep countersink. This countersink was milled with a conical precision cutter that can be bought in an ordinary hardware store (cost <5 US dollars). The countersink facilitates the insertion of an archived PTCB into the paraffin tissue punch and enables the construction of PTMAs with previously archived PTCBs using the widely distributed Beecher system. Moreover, this paraffin tissue punch can be used for other systems to create PTMAs, such as the low-budget systems designed by Vogel.