The pathogenesis of local recurrence of melanoma at the primary excision site.

Local recurrence of melanoma at the primary excision site may imply that the primary excision was incomplete or 'inadequate', and that the recurrence was due to retained primary melanoma cells or occult microsatellites in the adjacent tissue. Pathologists frequently report these tumours in the scar as recurrent or residual melanoma, without further qualification, apparently without considering the possibility that they may be metastases and manifestations of systemic disease. In this study, 17 of 19 cases of locally recurrent melanoma at the primary excision site showed the histological features of metastasis rather than residual incompletely excised primary melanoma. Because the prevention of local recurrence is the main reason given in recommendations for wide excision of melanoma beyond complete excision of the primary tumour itself, it is essential that surgeons and pathologists should classify these neoplasms precisely as either persistent incompletely excised primary melanoma or metastatic melanoma.