Tissue Processor

Abstract: We studied the effect of a fully automated microwave-assisted rapid tissue processor (RTP) on histologic examination and on the turnaround time for surgical pathology reports. A quality assurance program reviewed the histologic sections obtained by the rapid processing method for the last 3 calendar years. In addition, the histologic results from this method were compared blindly with those obtained from the conventional overnight tissue processing (CTP) method by 9 pathologists with different levels of experience. The surgical pathology turnaround times for 1 year of use of the RTP were compared with the last year for CTP. We found that the RTP reproducibly yielded histologic material comparable in quality to CTP. The turnaround time for surgical pathology reports was improved substantially, and, in particular, same-day reporting was achieved in approximately 55% of cases compared with fewer than 1% before use of the RTP. Moreover, use of the RTP enhanced safety by eliminating formalin and xylene from the procedure.

Abstract: The description describes a tissue processor (10) for processing tissue samples for histological analysis. The processor comprises two retorts (12, 14), baths (16-22), reagent containers (26), a pump (44), and valve. The valve distrubutes the reagent from one container to either retort. Separate reagent lines connect the wax baths to the retorts (the subject of one claim). A method is described (and claimed), of infiltrating a sample containin a reagent such as a dehydrating agent like an alcohol, where the infiltrating material is heated to a temperature at or above the boiling point of the reagent, to boil off the reagent when the tissue sample is contacted by the infiltrating material. Another claim defines the pressure in the retors as being reduced to lower the boiling point of the reagent.

Abstract: An improved microwave unit and tissue processor system incorporating the unit are provided for use in rapid tissue processing. The microwave unit may be comprised of an energy source, a waveguide transmitting the microwave energy to a reaction chamber, and the reaction chamber being adapted to process tissue specimens for histology. The unit provides gentle and uniform heating, with minimal heat loss and escape of volatile chemicals. The system may be operated continuously and/or batchwise, by manual operation or automatically. The automated system may be operated with continuous throughput to obtain the advantages of the invention such as, for example, rapid processing under two hours and/or preservation of cell structure and tissue architecture.

Abstract: A recently introduced histologic fixative (Universal Molecular Fixative [UMFIX]) has been shown to preserve macromolecules in tissue at ambient temperature. When UMFIX-exposed tissues are processed by a formalin-free, microwave-assisted rapid processing system, the resulting paraffin blocks retain good histomorphology and intact nucleic acids suitable for expression microarray analysis. Because UMFIX may be used as an alternative to formalin, the authors set out to study the effect of this new fixation and processing system on immunohistochemistry (IHC) by analyzing a range of human neoplastic and non-neoplastic specimens. Parallel slices from surgically removed specimens were fixed in formalin and UMFIX and processed in a rapid microwave-assisted tissue processor. IHC was performed following routine procedures. The staining for those antibodies that normally required antigen retrieval was carried out with and without that step. The intensity and pattern of reactions were compared in 144 tissue samples fixed by the two methods using 70 monoclonal and polyclonal antibodies. The intensity of IHC reactions for most cytoplasmic antigens was generally equal or stronger in UMFIX tissues. This was particularly true with intermediate filaments and HercepTest, where the antigen retrieval step became unnecessary. Conversely, there was a decrease in the intensity of reactions for HepPar1, bcl-2, and three nuclear antigens (Ki-67, TTF-1, and estrogen receptor). Increasing their exposure times optimized the sensitivity of the latter four antibodies. The study shows that IHC staining results of tissues fixed in UMFIX and processed by the microwave-assisted system are comparable to those obtained on formalin-fixed, similarly processed specimens. There is an enhancement of the sensitivity of few antibodies in UMFIX-exposed tissue, rendering antigen retrieval unnecessary. This increased sensitivity may be due to the effect of eliminating formalin from fixation and processing or the microwave energy.