One-step surgical removal of cutaneous melanoma with surgical margins based on preoperative ultrasound measurement of the thickness of the melanoma

Abstract

Background: Surgical margins of melanoma vary from 5 mm to 1 or 2 cm depending on histology thickness (Breslow). This approach usually requires two surgical steps: excisional biopsy and further re-excision according to histology thickness. A previous systematic review showed that measuring melanoma thickness with high-resolution ultrasound imaging equipment correlates well with histological measurement of melanoma thickness. Therefore, we routinely determined tumour sonographic thickness in order to perform surgery as a single step.

Objectives: To determine the proportion of patients who receive one-step surgery with adequate margins based on sonographic measurement of melanoma thickness and identify the reasons for differences between these two measurements.

Materials and methods: A retrospective series of patients with melanoma, in which thickness was measured by ultrasound (20 MHz) from April 2007 to December 2015 prior to surgery.

Results: Ninety-nine melanomas were treated, of which 78 were removed in a single step with surgical margins based on sonometric thickness measurements; 71 of these (91%, 95% CI: 82-96) did not require re-excision, five had excessive margins, and two had insufficient margins. The correlation between the histometric and sonometric measurements was good; r=0.88. Significant absolute difference between sonometric and histometric measurements was associated with thickness, ulceration, and size of tumours, based on bivariate analysis. Thickness remained the only significant factor based on multivariate analysis.

Conclusion: Measuring the thickness of melanoma with high-resolution ultrasound imaging equipment makes it possible to remove the melanoma in a single step with adequate margins in at least 82% of the cases in routine care.

Keywords: Breslow index; high-frequency ultrasound; imaging; medical decision; melanoma; surgical margin.