The Invasive Growth Potential of Residual Melanoma and Melanoma In Situ

BACKGROUND Residual melanoma and melanoma in situ (MIS), also referred to as marginally recurrent melanoma, continues to be a concern for all dermatologic surgeons. Little is known about the potential of these tumors to recur with a deeper invasive histology measured according to Breslow depth. OBJECTIVE To identify the clinical features and histologic, invasive potential of marginally recurrent melanoma and MIS. By having a more accurate understanding of marginally recurrent melanoma, we can better appreciate the consequence of inadequate excision and recognize the importance of improving initial treatments. MATERIALS AND METHODS An analysis was performed of 108 marginally recurrent melanoma and MIS cases based on prospective data collection. For each case, clinical data, including a comparison of Breslow depth from the time of primary treatment and salvage surgery for marginally recurrent tumor, were tabulated. RESULTS Of the 84 lesions initially treated as MIS, 19 (22.6%) recurred marginally with a histologically invasive component and a mean Breslow depth of 0.94 mm. Of the 24 patients diagnosed with invasive melanoma, eight (33.3%) had a deeper Breslow depth at the time of clinical recurrence than at the time of primary treatment. The change in Breslow depth for these eight cases was 1.53 to 2.83 mm. CONCLUSIONS Our findings demonstrate the invasive growth potential of MIS and invasive melanoma inadequately excised at the time of primary treatment. This finding illustrates the consequences of marginal recurrence and stresses the importance of accurate and complete removal of melanoma at the time of initial diagnosis and treatment. The authors have indicated no significant interest with commercial supporters.