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Published on: November 29, 2018
Tissue Contamination During Transportation of Formalin-Fixed, Paraffin-Embedded Blocks
Timothy Carll1, Christine Fuja1, Tatjana Antic1
1Department of Pathology, University of Chicago, Chicago, IL, USA.
Objectives:
Tissue carryovers are contaminants of surgical pathology cases in which extraneous tissue is incorporated into tissue blocks. Carryovers occur most frequently at the grossing or embedding stations, but little is published about them. We sought to analyze their transmission during transit to the histology lab.
Methods:
Cassettes of friable donor tissue were mixed with cassettes of spongy recipient tissue in formalin-filled containers and agitated by shipment via pneumatic tube. The tissue cassettes were processed, embedded as blocks, and cut as usual. Liquid samples were prepared from the submission containers as well as from workstation submission containers and histology tissue processor waste.
Results:
A high rate of contamination (14.9%) was observed under these artificial conditions. Friable donor tissue, including urothelium and colorectal adenocarcinoma, were promiscuous contaminants, as were placental villi. Fluid from submission containers showed viable tumor cells and fragments, which were also present in workstation submission containers and in tissue processor waste fluid.
Conclusions:
This study implicates liquid transport media as a possible avenue of contamination during submission and transportation of tissue cassettes for histologic processing. Attention should be given to the friability of submitted tissue and physical agitation of the cassettes in transit. Such contaminants may be present in the fluid in tissue submission bins and in tissue processor fluid.
Insights
Tissue carryovers, or extraneous tissue in surgical pathology blocks, can contaminate samples during transit. This study found that liquid transport media and friable tissues significantly increase contamination risk in histology labs.
Area of Science:
- Surgical Pathology
- Histology
- Laboratory Contamination
Background:
- Tissue carryovers are unintended contaminants in surgical pathology, often occurring during grossing or embedding.
- Limited research exists on how tissue carryovers are transmitted during transit to histology labs.
Purpose of the Study:
- To analyze the transmission of tissue carryovers during the transportation of tissue cassettes to the histology lab.
- To identify potential sources and pathways of contamination during specimen submission and transit.
Main Methods:
- Friable donor tissue cassettes were mixed with spongy recipient tissue cassettes in formalin.
- Agitation was simulated via pneumatic tube shipment.
- Liquid samples were collected from containers, workstations, and tissue processor waste for analysis.
Main Results:
- A significant contamination rate of 14.9% was observed under simulated transport conditions.
- Friable tissues like urothelium, colorectal adenocarcinoma, and placental villi acted as potent contaminants.
- Viable tumor cells and tissue fragments were detected in transport fluids, workstation containers, and processor waste.
Conclusions:
- Liquid transport media can facilitate tissue carryover contamination during specimen submission and transit.
- The friability of submitted tissue and physical agitation during transport are critical factors.
- Contaminants may be present in submission bin fluids and tissue processor waste, necessitating improved handling protocols.
