Background: The frequency of in situ melanoma is increasing, and it is often diagnosed fortuitously by histology.
Methods: We retrospectively reviewed 121 melanomas in situ in 113 patients with the aim of identifying the clinical features of, and optimal surgical treatment for this cutaneous malignancy. Treatment was limited surgery with 3 mm margins of excision in 69 cases (57%) and wider margins of excision (more than 3 mm) in 52 cases (43%). The lesions had a median diameter of 1 cm (range, 2-35 mm) and were generally macular (92% of cases) asymmetric (87%), with an irregular border (88%) and nonuniform pigmentation (98%), usually in shades of brown (41%) and black (48%). These features had permitted a clinical diagnosis of melanoma or suspected melanoma in 62% of cases and of doubtful nevus in an additional 18% of cases.
Results: At a median follow-up of 4 years, there were six local recurrences (three treated by limited surgery and three by wider excision), all in situ melanomas.
Conclusions: The typical clinical features of melanoma in situ, which are similar to those of early invasive melanoma, are usually sufficiently distinctive to suggest the clinical diagnosis of melanoma or suspected melanoma. Except for large size and superficially extended lesions (larger than 2 cm), adequate treatment is excision with 3 mm margins, although larger lesions (larger then 2 cm) may have an appreciable incidence of local recurrence.