Surgical excision margins for melanoma in situ

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Summary

Introduction

Melanoma in situ (MIS) is a non-invasive lesion accounting for up to 27% of all melanomas by Coory et al. (2006).1 MIS may be a precursor to invasive disease. The Lentigo Maligna (LM) subgroup of MIS carries upto a 4.7% lifetime risk of developing an invasive component by Agarwal-Antal et al. (2002).2 Surgical excision is recommended however other modalities of treatments are possible. In this study we aim to assess whether histological margins following excision of in situ melanoma has any bearing on recurrence or progression to malignancy.

Method

We retrospectively reviewed data accumulated on all melanomas referred to the hospital between the dates of February 2001 to February 2009. We identified all patients with melanoma in situ and for these patients recorded age, sex, anatomical site of lesion, histological type, histological excision margin, recurrence after excision and transformation to malignant melanoma.

Results

A total of 2121 patents were identified having been diagnosed and treated for melanoma of which 192 cases were identified with melanoma in situ representing 9.1% of all melanomas treated. 38% of all the lesions were of the LM subgroup. We noted a higher incomplete excision rate in this subgroup (p < 0.01) compared to the non-LM subgroup. We only noted two recurrences following complete excision (1.1%) and one recurrence in lesions completely excised with histological margins less than 2 mm (1.4%). Both of the lesions that recurred following complete excision were LM lesions. Recurrence following complete excision of LM was 2.9%.

Conclusion

Our data suggests that MIS lesions that were not LM and adequately excised even with narrow margins are unlikely to recur therefore reducing the need for wider excision. LM however poses a more challenging clinical problem not only with the higher inadequate primary excision and higher recurrence rates following excision but also the fact that it occurs in much older patients who may be less able to tolerate more extensive surgery. In keeping with the literature we would suggest treating LM lesions more aggressively if possible.

Introduction

Melanoma in situ (MIS) is a non-invasive lesion accounting for up to 27% of all melanomas.1 A melanoma in situ may be a precursor to invasive disease. Lentigo maligna (LM) is a sub group of melanoma in situ occurring most commonly in sun damaged skin and is rarely seen in young patients. LM is estimated to carry a 4.7% lifetime risk of developing an invasive component.2 Surgical excision is recommended with guidance offered on the surgical margin of excision. However other modalities of treatments are possible. In this study we aim to assess whether histological margins following excision of in situ melanoma has any bearing on recurrence or progression to malignancy.

Section snippets

Method

We retrospectively reviewed data accumulated on all melanomas referred to the hospital between the dates of February 2001 to February 2009, regardless of which speciality they were treated by. We identified all patients with MIS and for these patients recorded age, sex, and anatomical site of lesion, histological type, histological excision margin, recurrence after excision and transformation to malignant melanoma. Statistical analyses were performed using the Fishers exact test.

Results

A total of 2121 patents were identified having been diagnosed and treated for melanoma of which 192 cases were identified with melanoma in situ representing 9.1% of all melanomas treated. There was a slightly higher incidence in female of 53%–47% in males. The average age of patients was 59.1 years.

Discussion

Frameworks and guidelines for the management of malignant melanoma have evolved over the last thirty years as a consequence of well-planned multi center research resulting in a depth and breadth of clinical knowledge and histological understanding of malignant melanoma. Melanoma is situ although accounting for up to 27% of all melanomas is less well understood.1

MIS is a non-invasive lesion but despite this it can be a precursor to invasive disease. Clinically it presents as a dark irregularly

Conflict of interest

None.

Funding

None.

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