Melanoma in Situ Given Wider Berth in New Excision Guidelines

05 Apr 2018

Alice Cran

by Ms Alice Cran

Dermatologist mapping a patient's moles

Determining the margin of normal looking surrounding skin that should be included when treating melanoma can be a controversial topic for skin cancer clinicians. Take too little away and the potential for cancer recurrence rises. Remove too much surrounding skin and the patient is exposed to an increased risk of complications and poorer cosmesis. Finding a safe margin that achieves complete histological clearance has been one of the topics considered as part of a detailed literature review of melanoma management conducted by the Melanoma Institute of Australia in conjunction with Cancer Council Australia. The results of that review were recently published in the Medical Journal of Australia.

As part of that review the 2008 evidence-based clinical practice guidelines for the management of melanoma have been updated. The new recommendations for definitive wide local excision of primary cutaneous melanoma are:

  • Melanoma in situ: 5-10mm margins
  • Invasive melanoma (pT1) ≤ 1.0mm thick: 1cm margins
  • Invasive melanoma (pT2) 1.01-2.00mm thick: 1-2cm margins
  • Invasive melanoma (pT3) 2.01-4.00mm thick: 1-2cm margins
  • Invasive melanoma (pT4) > 4.00mm thick: 2cm margins

When compared with the 2008 guidelines, the revised excision margins for invasive melanoma remain unchanged. The only modification is the excision margin for melanoma in situ; where the clinical evidence now supports a wider excision margin of 5-10mm in order optimise the chance of achieving complete histological clearance.

The updated guidelines also provide useful practice points on diagnosis and management of melanoma, such as the method of measuring total radial excision margins- a clinical point that also influences MBS item selection. Removal of skin cancer lesions has been the subject of Medicare audits in the past and clinicians should ensure strict compliance with item descriptors.  

MDA National assists its Members in Medicare audits and to obtain assistance please contact us.

This blog contains general information only. We recommend you contact your medical defence organisation or insurer when you require specific advice in relation to medico-legal matters.



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