Tissue Contamination During Transportation of Formalin-Fixed, Paraffin-Embedded Blocks.
Author(s): Carll T, Fuja C, Antic T, Lastra R, Pytel P
Publication: Am J Clin Pathol, 2022, Vol. 158, Page 96-104
PubMed ID: 35195717 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to determine the incidence of contamination of formalin-fixed, paraffin-embedded (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). 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 instead of by courier.
Conclusion of Paper
Of the 121 cassettes transported by pneumatic tube system (PTS), 18 contained carryover tissue contamination within their FFPE block upon histologic review (14.9% of blocks); both porous and friable tissue specimens were contaminated, and some specimens included contaminants from multiple sources. The most common sources of tissue contamination were urothelial carcinoma (9 blocks), colorectal adenocarcinoma (8 blocks), and placental villi (9 blocks). Although the exact number of tissue cassettes in each run was not specified there were multiple, and at least one contaminated FFPE block occurred on each of the 10 experimental runs (100%). Placing tissue specimens in an additional layer of containment reduced but did not prevent contamination with carry over tissue, as 16.2% (6/37) of tissue in mesh biopsy bags, 5.4% of tissue packed in filter paper (2/37), and 20% (2/10) of tissue packed between biopsy sponges displayed tissue carryover(s) compared to the 21.7% (8/37) of tissue specimens that were placed directly in the tissue cassette.
Cytospin preparations from the tissue transport fluid included viable cells and numerous fragments of friable benign tissue. Transport fluid sampled from runs where all tissue specimens were placed in an additional layer of containment had a nonsignificantly lower number of contaminating viable epithelial (cassette only = 57.8, biopsy sponge= 22.2, lens paper= 27.2, mesh bag=11.9 cells per field of view) and inflammatory cell nuclei (cassette only = 48.2, biopsy sponge= 42.5, lens paper= 35.0, mesh bag=42.1 cells per field of view) than transport fluid from runs where tissue was just placed within a cassette. Multiple tissue and cell contaminants were identified from scrapings of the exterior of the mesh biopsy bags after pneumatic tube transport. Further, both the temporary submission bins and the tissue processor waste bins contained multiple tissue fragments after a day of use, indicating that they may be another vehicle of contamination.
Studies
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Study Purpose
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.
Summary of Findings:
Of the 121 cassettes transported by pneumatic tube system (PTS), 18 contained carryover tissue contamination within their FFPE block upon histologic review (14.9% of blocks); both porous and friable tissue specimens were contaminated, and some specimens included contaminants from multiple sources. The most common sources of tissue contamination were urothelial carcinoma (9 blocks), colorectal adenocarcinoma (8 blocks), and placental villi (9 blocks). At least one contaminated FFPE block occurred on each of the 10 experimental runs (100%). Placing tissue specimens in an additional layer of containment reduced but did not alter prevent contamination with carryover tissue as 16.2% (6/37) of tissue in mesh biopsy bags, 5.4% of tissue packed in filter paper (2/37), and 20% (2/10) of tissue packed in between biopsy sponges displayed tissue carryover(s) compared to the 21.7% (8/37) of tissue specimens that were placed directly in the tissue cassette.
Cytospin preparations from the tissue transport fluid included viable cells and numerous fragments of friable benign tissue. Transport fluid sampled from runs where all tissue specimens were placed in an addition layer of containment had a nonsignificantly lower number of contaminating viable epithelial (cassette only = 57.8, biopsy sponge= 22.2, lens paper= 27.2, mesh bag=11.9 cells per field of view) and inflammatory cell nuclei (cassette only = 48.2, biopsy sponge= 42.5, lens paper= 35.0, mesh bag=42.1 cells per field of view) than transport fluid from runs where tissue was just placed within a cassette. Multiple tissue and cell contaminants were identified from scrapings of the exterior of the mesh biopsy bags after pneumatic tube transport. Further, both the temporary submission bins and the tissue processor waste bins contained multiple tissue fragments after a day of use, indicating that they may be another vehicle of contamination.
Biospecimens
Preservative Types
- Formalin
Diagnoses:
- Neoplastic - Benign
- Neoplastic - Carcinoma
Platform:
Analyte Technology Platform Morphology H-and-E microscopy Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Acquisition Type of collection container/solution Tissue cassette
Mesh bag with tissue cassette
Lens filter paper with tissue cassette
Biopsy sponge with tissue cassette
Storage Within hospital transportation method Pneumatic tube system
Hand-delivered