The prognosis and treatment of true local cutaneous recurrent malignant melanoma

The prognosis and treatment of true local cutaneous recurrent malignant melanoma is presently unknown. We define this entity as melanoma bearing an in situ component that recurs contiguous with the scar of the primary excision. Although previously uncommon, the incidence of true local recurrent melanoma may rise due to the recent use of more narrow margins for excision of thin primary melanoma.

We hypothesized that there is a difference in prognosis between true local cutaneous recurrent melanoma versus local recurrence from satellite or in-transit metastases. Also, we defined guidelines for the surgical management of true local cutaneous recurrent melanoma.

We calculated the surgical margin necessary to reach a tumor-free plane using Mohs surgery in 50 patients with true local recurrent melanoma. Patient survival was determined by the Kaplan-Meier method.

Seventy-six percent of the tumors were completely excised using a margin of less than 1 cm. However, a margin of up to 2 cm was required to successfully treat all 50 patients. Thicker tumors did require significantly larger margins. The Kaplan-Meier 5-year overall and melanoma survival rates were 89% and 98%, respectively. The 5-year disease-free survival rate was 66%.

The prognosis of true local recurrent melanoma is related to tumor thickness. We recommend full-thickness excision of the entire old scar including a 2-cm margin or Mohs surgery if a narrower margin of resection is desired.