Formalin is deleterious to cytoskeleton proteins: do we need to replace it by formalin-free Kryofix?

Formalin is hazardous for the environment and for the laboratory personnel and deleterious to cytoskeleton proteins. The pathology and anatomy laboratory can be formalin-free when Kryofix is used as a substitute fixative. In four years experience with Kryofix, we learned that immunostaining on paraffin sections is reproducible and of excellent quality. The current study concerns the comparison of interfilament staining on paraffin sections made from formalin or from Kryofix-treated tumors. For both keratin and vimentin there were false-negative findings in the formalin-fixed tumors. Of these two, vimentin was het most susceptible to formalin fixation. Three of the ten adenocarcinomas were positive for both keratin and vimentin, indicating that this double staining pattern is not uncommon. Postfixation of Kryofix-treated tissue with formalin results in false-negative immunostaining.