Determination of preexcision surgical margins of melanomas from fixed-tissue specimens

The shrinkage of cutaneous surgical specimens of 199 malignant melanomas was analyzed. A formula was derived that makes it possible to calculate the in vivo (preexcision) specimen diameter from the in vitro (fixed-tissue) specimen diameter. The age of the patient was found to significantly influence specimen shrinkage and was incorporated into this shrinkage formula. The calculated in vivo specimen diameter was then used to determine the width of the in vivo surgical margins with reasonable accuracy. Thus this method permits calculation of the width of surgical margins from fixed-tissue specimens.