Punch biopsy of the skin: effect of tissue fixation with CO2-freezing. An experimental study.

Abstract

ABSTRACTThe effect of tissue fixation with CO2‐freezing on the size and quality of punch biopsies was studied post mortem. Four millimeter punch biopsies were taken from the abdominal skin with a motor drill operating at 250 RPM, before and after freezing with CO2 in acetone. The dry defatted weight was determined from 32 biopsies in each series, and light microscopy was performed on 16 biopsies in each series after setting up a double blind system.The dry weight of the whole biopsy was higher (p<0.05) after CO2‐freezing, but the weight of the epidermis/dermis alone was the same. The conical shape of the punch biopsies was due to retraction occurring during and after biopsy and not to loss of tissue.In the CO2‐frozen series, there were more (p<0.001) biopsies cylindrical in shape, more (p<0.001) biopsies including fascia and muscle, fewer (p<0.001) biopsies with trauma, more (p<0.01) biopsies with subcutaneous tissue represented, in a larger amount (p<0.001), and more (p<0.001) biopsies optimal for microscopy.After tissue fixation, the quality of the biopsies for microscopy was much better with regard to tissues represented and tissue archilecture. Further efforts to develop an easy in vivo technique for tissue fixation are indicated.