The Biospecimen Research Database

The purpose of this study was to determine the incidence of contamination of FFPE blocks containing porous benign tissue specimens (lung parenchyma, placental parenchyma) with friable carcinoma tissue (papillary urothelial carcinoma, colorectal adenocarcinoma, lung adenocarcinoma, and clear cell renal cell carcinoma) and to identify the stage of processing where contamination occurred. Contamination rates were also compared among tissues that were placed directly in a tissue cassette with those that had an additional layer of containment. The study originated when a higher incidence of FFPE contamination with "carryover" tissue was reported by the reviewing pathologist after tissue cassettes were transported from the grossing room to the histology lab via a pneumatic tube system (PTS) during hospital construction; given that the affected specimens underwent grossing and processing at different stations, transport via PTS was identified as the probable source of contamination. In total, 121 FFPE specimens (44 friable carcinoma tissues and 77 porous benign tissues) were analyzed over10 transport runs. During each transport run, friable carcinoma tissue and spongy benign tissue were placed directly in tissue cassettes or placed in mesh biopsy bags, packed between biopsy sponges, on in filter paper within the tissue cassette and then placed in a "submission bin" containing 10% neutral buffered formalin (NBF) for an unspecified period of time. Tissue cassettes were then transferred to a 500 mL transport container with approximately 200 mL of 10% NBF and transported to the histology lab by PTS (details of the length, speed, and braking of PT transport were not provided). Samples of fluid from the submission bin (50 mL), transport container (50 mL), as well as tissue processor waste (10 mL collected after the fluid was allowed to settle for 24 h before sampling) were collected, centrifuged (speed and duration not provided), resuspended in 10% NBF, and a drop was prepared on a cytospin slide.  For a subset of specimens transported in mesh bags, a sample was collected by scraping the outside of the mesh biopsy bag, centrifuged, and prepared as a HistoGel cell block.  Single sections from FFPE blocks were mounted to glass slides, stained with hematoxylin and eosin, and reviewed by a pathologist.  Floaters (debris that is introduced when mounting sections onto slides) were identified and excluded as "contamination".  When observed, tissue carryovers were identified, their tissue of origin was identified by the pathologist based on histomorphological characteristics.