Background
Achieving clear surgical margins in excision of melanoma in situ (MIS) is challenging. The concurrent Australasian guidelines on melanoma recommended an excision margin of 5-10mm. This case describes our experience of using staged contoured marginal excision (CME) as an alternative technique to achieve clearance of a persistent residual MIS after multiple failed wide local excisions (WLE).
Case Description
A 77-year-old woman was diagnosed with a left arm pT3a malignant melanoma by excision biopsy. Three subsequent WLEs with adequate clinical margins all showed histology that was clear of invasive melanoma but MIS persistently present peripherally. A CME technique was used to achieve histological clearance. Two 5mm wide strips of skin were excised 5mm beyond the macroscopic extent of the pigmented lesion. Paraffin embedded radially-sliced sections from the excision was evaluated for residual disease. The positive 12 o’clock margin subsequently excised with another 5mm rim of tissue which was extended into two triangular skin flaps proximally and distally to allow the wound closure in an ellipse. 10mm margin clearance was achieved with direct closure of the wound within a single 24-hour period.
Discussion
This is the first case we are aware of using CME for MIS in Australasia. Benefits include achieving clearance of a difficult to manage MIS within a 24-hour period without undue risk of disfigurement or prolonging the period of open wounds pending histological analysis. CME requires close support from Histopathology and we have been advised that this technique was superior to slow Mohs and Mohs surgery.
Conclusion
Staged CME is a well described technique overseas and we have had a positive experience utilising it in our centre. In the future this will be a valuable addition to our armamentarium in managing challenging MIS in anatomically sensitive areas.