Narrower surgical margins might be sufficient in invasive horizontal growth phase melanoma

The delineation of horizontal and vertical growth phases in primary cutaneous melanoma has contributed to our understanding of melanoma progression. Horizontal growth phase invasive melanomas are now believed to metastasize very rarely. Consequently, some of us have started to treat these lesions with very limited surgical margins, assuming that in terms of biological behavior this type of melanoma is more similar to an in situ than an invasive lesion.

Between January 1997 and December 2001 42 lesions of this type in 41 patients (24 women and 17 men) were treated in the outpatient clinic under local anesthesia. The excision margin was half a centimeter and the subcutaneous fat was cleared in most cases to the deep fascia, which was conserved. Loss was made good by direct tissue closure. All patients had undergone an excisional biopsy before definitive surgery. The size of the lesions ranged from 2 mm to 19 mm in maximum linear extent (median 7 mm). Lesion thickness ranged from 0.11 mm to 0.58 mm (median, 0.27 mm).

The median follow-up was 47 months (range, 26-83). During this period none of the patients had locoregional or distant relapses.

This preliminary report seems to corroborate the assumption that horizontal growth phase melanoma is not an aggressive lesion and might therefore be cured by non-aggressive surgery. The proper treatment of such lesions might be a surgical excision at half a centimeter distance from the biopsy scar. This approach may produce very good cosmetic results, while keeping the costs and required resources to a minimum.