Shrinkage of cutaneous specimens: formalin or other factors involved?

Background: Shrinkage of cutaneous tissue during processing is a source of controversy. This study was designed to prospectively determine tissue shrinkage at two intervals: 1 min after excision and after 24 to 48 h of formalin fixation. Secondarily, gender, age, site, prior biopsy scar and solar elastosis were evaluated with respect to shrinkage. Methods: Ninety-seven cutaneous specimens were measured prior to excision, 1 min after removal and after 24 to 48 h of formalin fixation. Width of prior biopsy scar, damage to elastic fibers and solar elastosis were subjectively quantified. Results: Significant tissue shrinkage occurred immediately after excision, prior to formalin fixation. Mean shrinkage (95% confidence interval): length 20.66% +/- 2.15% and width 11.79% +/- 2.35%. Range of shrinkage: length 0 to 41.18% and width -18.75% (indicating expansion) to 37.50%. Patient age was significant; shrinkage decreased 0.3% per year of increasing age. Site was less significant; trunk excisions measured 5% greater shrinkage than head/neck excisions. As solar elastosis increased, shrinkage decreased. Conclusions: Cutaneous tissue shrinkage following excision is primarily because of intrinsic tissue contractility. Increasing patient age and solar elastosis correlate with less shrinkage. The clinicians and dermatopathologists must be cognizant of the expected shrinkage of submitted specimens for settling discrepancies within the medical record.