Staged excision versus Mohs micrographic surgery for lentigo maligna and lentigo maligna melanoma

Abstract

Background: Lentigo maligna (LM) is a relatively common tumor with increasing prevalence and substantial morbidity. A variety of treatment modalities are available, though margin-control surgery offers the highest cure rate. We were interested in comparing long-term outcomes of Mohs micrographic surgery (MMS) versus staged excision with permanent sections (SE) for treating LM or LM melanoma (LMM).

Methods: Comparative study consisting of retrospective chart review from our private practice.

Results: Fifty-seven patients (31 male, 26 female, mean age at diagnosis 69.1 +/- 10.1 years) were treated in our office for LM (50) or LMM (9) between January 1986 and December 2001. Forty-one tumors (71%) were located on the head and neck. Fifty-three of the 59 tumors (90%) were primary, and 6/59 (10%) were recurrent at the time of initial treatment. Forty-one tumors (36 LM, 5 LMM) were treated with SE, and 18 (14 LM, 4 LMM) were treated with MMS. The mean preoperative lesion size (1.5 +/- 0.2 cm2 for SE; 1.2 +/- 0.4 cm2 for MMS), mean postoperative defect size (7.1 +/- 1 cm2 for SE; 7.1 +/- 1.4 cm2 for MMS), and the ratio of postoperative defect to preoperative lesion size (7.9-fold increase for SE, 11.2-fold increase for MMS) were similar between the cohorts. Mean number of stages for clear margins were similar, with 1.8 +/- 0.2 stages (range: 1-7) for SE and 2.0 +/- 0.2 stages (range: 1-4) for MMS; clear margins were obtained in one or two stages in 85% of cases for SE and in 67% for MMS. Three recurrences (3/41; 7.3%) occurred in the SE group while 6 recurrences (6/18; 33%) occurred in the MMS group (P < .025). The mean follow-up duration was 95 months (range: 60-240) in the SE group and 117.5 months (range: 61-157) in the MMS group.

Limitations: Results are limited to a single practice site and fewer patients underwent MMS compared to SE. Patients were not randomized as cases were ascertained retrospectively.

Conclusion: Staged excision of LM and LMM is associated with a significantly lower recurrence rate with no difference in surgical defect size compared to MMS. To our knowledge, this is the first study directly comparing these two surgical techniques for managing this form of melanoma. Our extended follow-up duration exceeds that of most previous reports.