Evaluation of the difference in surgical margin values in excisional skin lesions during surgery and after formalin fixation

Background: Surgical margin determination in malignant lesions is essential and has a direct impact on the choice of postoperative treatments and patient follow-up. Therefore, the processes affecting this variable are worth exploring. This study aimed to evaluate the difference in surgical margin values in excisional skin samples during surgery and after formalin fixation. Methods: A cross-sectional study was performed on forty randomly selected patients with benign and malignant skin lesions who were referred to the plastic surgery ward of Ghaem Hospital in Mashhad from November 2018 to January 2019. Malignant and benign skin lesions were excised with a healthy margin, then the specimens were sent to the pathologist in a formalin-containing container. The amount of tissue shrinkage and the factors affecting them were compared. Results: Among all 40 participants about 57.5% of the them were male and 42.5% were female. The mean age of the patients was 66.55±14.53 years. Surgical margin was evaluated in three patterns: before surgical incision and after surgical incision (P<0.001), before surgical incision and after formalin fixation (P<0.001), after surgical incision and after formalin fixation (P=0.02). In this study, the relationship between the age and initial length of the skin lesion with sample shrinkage was not statistically significant. Conclusion: The results of this study showed that tissue shrinkage occurs both after incision and after formalin fixation. The highest rate of shrinkage was seen after surgical excision, which was due to the elasticity of the tissue itself. Increasing age and initial length of skin lesion did not affect this shrinkage. Also tumoral tissue contracted less than healthy tissue due to flexibility of fatty tissue and water and lipid content.