Modified-Mohs surgery optimal for the management of melanoma in-situ

29/12/15 22:00

A new study published in the November 2015 edition of the British Journal of Dermatology, adds further confirmation as to the optimal treatment for melanoma in-situ (the earliest/thinnest and most common form of melanoma).

This has been Dr Gunson's treatment of choice for this form of melanoma for many years. The technique is a modification of the standard Mohs Micrographic surgery method. It is often very difficult to accurately interpret melanoma cells on the frozen section used during standard Mohs surgery for other skin cancers. Utilising a paraffin-based tissue sectioning for melanoma provides increased accuracy. Unfortunately, paraffin-sectioning takes longer and requires sending the specimen to an off-site laboratory. With this comes delay and logistical issues. However, as this new study has again demonstrated, the superior results make the additional time and hassle well worthwhile, leading to significant improvements in cure rates, compared with tradition surgical excision.

The fundamental difference is that Mohs-type analysis seeks to examine 100% of the peripheral margin of the excision. Standard paraffin-sectioning relies on a small number of cross-sections cut as you would when slicing a loaf of bread. The biology of this type of melanoma is renown for extensive sub-clinical spread (melanoma cells extending well past that seen on the surface of skin). Random cross-sectional analysis examines a very small proportion of the total peripheral margin of the excision, increasing the chances of melanoma cells being left behind following a "complete" standard excision.

The Modified Mohs technique takes place in a staged-fashion with the highly accurate pathology analysis occurring overnight. The wound is dressed and the patient is able to return home. The results are available the following day. Further targeted excision of any residual melanoma can then taken if necessary, and sent for the same rigorous examination. Once no further melanoma cells are seen, the wound is reconstructed in the usual manner. The patient and doctor can then share confidence that the tumour has been removed with the highest chance that it will not recur at a later date.