Sponge artifact in biopsy specimens.

We describe a sponge-induced artifact in histologic sections of small biopsy specimens. The artifacts are angulated, often triangular holes within the tissue. They appear to be introduced as individual sponge barbs become embedded in the perimeter of biopsy specimens during tissue processing. The artifact is generally of little importance, but in certain specimens, such as needle biopsies of the kidney or liver, it may occasionally obscure important information. Other methods, such as lens paper wrapping, may be superior in these situations. The utility of the tissue cassette sponge, in most situations, outweighs the artifact.