Recurrence Rate of Melanoma in Situ when Treated with Serial Disk Staged Excision: A Case Series

Staged melanoma excision requires larger margins for tumor clearance and results in low rates of recurrence

There is controversy regarding the optimal surgical modality and ideal recommended margins for treating melanoma in situ (MIS) and invasive melanoma (IM). Although wide local excision is recommended, staged excision offers excellent margin control and low recurrence rates. In this manuscript, we reviewed a 10-year experience of staged excisions for the treatment of MIS and IM. A retrospective review was performed of 130 MIS and 32 IM cases treated with staged excision from April 2012 to April 2022. Staged excision was performed on the head and neck in 102 (79%) MIS and 23 (72%) IM cases. Approximately 10% of cases required surgical margins above the current recommendations (11 (9%) MIS and 6 (19%) IM). Twenty-three (19%) MIS and 7 (22%) IM cases required more than one excision to obtain clearance. Recurrence rates among MIS and IM were 0.0% and 0.6%, respectively. Upstaging occurred in 5 (4%) MIS and 7 (22%) IM cases. Complex repairs were performed on 82 (63%) MIS and 17 (53%) IM cases. Our findings revealed that staged excision provides effective margin control and low recurrence rates. Approximately 10% of patients required margins greater than the current recommendations, leading to larger defects and more complex repairs.

Melanoma In Situ: A Critical Review and Re-Evaluation of Current Excision Margin Recommendations

Most international clinical guidelines recommend 5-10 mm clinical margins for excision of melanoma in situ (MIS). While the evidence supporting this is weak, these guidelines are generally consistent. However, as a result of the high incidence of subclinical extension of MIS, especially of the lentigo maligna (LM) subtype, wider margins will often be needed to achieve complete histologic clearance. In this review, we assessed all available contemporary evidence on clearance margins for MIS. No randomized trials were identified and the 31 non-randomized studies were largely retrospective reviews of single-surgeon or single-institution experiences using Mohs micrographic surgery (MMS) for LM or staged excision (SE) for treatment of MIS on the head/neck and/or LM specifically. The available data challenge the adequacy of current international guidelines as they consistently demonstrate the need for clinical margins > 5 mm and often > 10 mm. For LM, any MIS on the head/neck, and/or ≥ 3 cm in diameter, all may require wider clinical margins because of the higher likelihood of subclinical spread. Histologic clearance should be confirmed prior to undertaking complex reconstruction. However, it is not clear whether wider margins are necessary for all MIS subtypes. Indeed, it seems that this is unlikely to be the case. Until optimal surgical margins can be better defined in a randomized trial setting, ideally controlling for MIS subtype and including correlation with histologic excision margins, techniques such as preliminary border mapping of large, ill-defined lesions and, most importantly, sound clinical judgement will be needed when planning surgical clearance margins for the treatment of MIS.

Histological Peripheral Margins and Recurrence of Melanoma In Situ Treated with Wide Local Excision

Background

The incidence of melanoma in situ (MIS) is increasing faster compared to invasive melanoma. Despite varying international practice, a minimum of 5 mm surgical excision margin is currently recommended in the UK. There is no clear guidance on the minimum histological peripheral clearance margins.

Aim

This study compares the histological peripheral clearance margins of MIS using wide local excision (WLE) to the rate of recurrence and progression to invasive disease.

Methods

A retrospective single-center review was performed over a 5-year period. Inclusion criteria consisted of MIS diagnosis, ≥16 years of age, and treatment with WLE with curative intent. Those patients with a recurrence of a previous MIS or with a reported focus of invasion/regression were also included. Clinicopathological data and follow-up were recorded.

Results

167 MIS were identified in 155 patients, 80% of which were lentigo maligna subtype. Of patients with completely excised MIS on histology (>0 mm), 9% had recurrence with a median time to recurrence of 36 months. Three (1.8%) cases recurred as invasive disease. Age, MIS site, MIS subtype, and histological evidence of foci of invasion/regression did not predict recurrence nor progression to invasive disease (p > 0.05). The recurrence rate of MIS with a histological excision margin ≤3.0 mm was 13% compared to 3% in those with histology margins of >3.0 mm (p=0.049).

Conclusion

A histological peripheral clearance of at least 3.0 mm is advocated to achieve lower recurrence rates. The follow-up duration should be reviewed due to the median recurrence occurring at 36 months in our cohort. Cumulative work on MIS needs to be collated and completed in a large multicenter study with a long follow-up period.