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Problems in Histopathological Technique
Prepared by
ROY ELLIS
IMVS Division of Pathology
The Queen Elizabeth Hospital
Woodville Road, Woodville, South Australia 5011
Email: roy.ellis@imvs.sa.gov.au
Grid-like impression artefact in small biopsies after using sponge pads to hold biopsies during processing
This is a soft tissue biopsy stained with Haematoxylin and Eosin and clearly showing visible triangular spaces within the tissue which are caused by tiny spikes in a sponge biopsy pad. When one looks closely at the triangular margins the tissue is compressed and staining is more eosinophilic.
This can be avoided by allowing the tissue to fix before placing it into the sponge pad because after fixation the surface is firmer and less prone to indentation. If the fresh biopsy is required urgently a shallow depression or linear slice can be cut in the sponge pad so that the specimen is not compressed as it is fixing.
Bayer-Sakura, who market Tissue Tek also sell a small metal cage with very fine wire, that can be used instead of sponge pads. The cages must be well washed before use since they tend to shed very fine metal filings which can find their way into the embedded tissue and damage sections and knives.
Tea bags, gauze and filter paper can also be used but care is still required since fibres from all of these items can stick to the surface of fresh tissue unless the item is first moistened with fixative before use.
The following is a section of spleen stained with haematoxylin and eosin and showing Gelfoam stuck to the surface of the capsule. Gelfoam is used to staunch bleeding during surgical procedures. The surface of fresh tissue is quite sticky until it is fixed.
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© Roy C. Ellis 2002