From the Guidelines
Melanoma in situ does not typically require a Mohs procedure for removal, and the standard treatment is wide local excision with a 0.5 to 1 cm margin of normal-appearing skin around the visible tumor. This approach is based on the recommendations from the Journal of the American Academy of Dermatology 1, which suggests that surgical excision with histologically negative margins is the first-line treatment for primary cutaneous melanoma, including melanoma in situ. The guidelines recommend wide excision with 0.5- to 1.0-cm margins for melanoma in situ, and Mohs micrographic surgery may be utilized in specific cases, such as on the face, ears, or scalp, for tissue-sparing excision and exhaustive histologic assessment of peripheral margins 1.
Some key points to consider when treating melanoma in situ include:
- Wide local excision with a 0.5 to 1 cm margin is the standard treatment 1
- Mohs micrographic surgery may be considered in certain cases, such as in cosmetically sensitive areas or where tissue preservation is critical 1
- The goal of treatment is to completely remove the cancer cells while they are still confined to the epidermis and have not invaded deeper tissues
- Conventional excision with pathologic examination of the margins is generally the preferred approach, as it allows for complete histological evaluation of the specimen 1
It's essential to note that the treatment approach may vary depending on the specific location and characteristics of the melanoma in situ, as well as the patient's individual needs and preferences. However, based on the current evidence, wide local excision with a 0.5 to 1 cm margin remains the primary treatment for melanoma in situ, with Mohs surgery being considered in select cases 1.
From the Research
Mohs Procedure for Melanoma In Situ
- The Mohs procedure is a valuable option for removing melanoma in situ, especially for lesions that are clinically ill-defined 2.
- Studies have shown that Mohs micrographic surgery (MMS) can achieve high rates of complete excision and low local recurrence rates for melanoma in situ (MIS) 3, 4, 5.
- A study published in the Journal of the American Academy of Dermatology found that MMS resulted in a local recurrence rate of 0.1% for MIS of the trunk and proximal extremities 3.
- Another study published in JAMA Dermatology found that the overall recurrence rates were 1.8% for MMS and 5.7% for wide local excision (WLE) 4.
- A retrospective review of 657 melanomas treated with modified Mohs micrographic surgery (mMMS) found a local recurrence rate of 1.98% and a 5-year melanoma-specific survival rate of 99.0% 5.
Comparison with Wide Local Excision
- Studies have compared the outcomes of MMS and WLE for MIS, with some finding similar recurrence rates and survival rates 4, 6.
- A study published in The Journal of Dermatological Treatment found that MMS and WLE had similar cancer-specific survival rates and overall survival rates for head and neck melanoma in situ 6.
- Another study published in JAMA Dermatology found that the 5-year recurrence rate was 1.1% for MMS and 4.1% for WLE, although this difference was not statistically significant 4.
Surgical Margins
- A study published in the Journal of the American Academy of Dermatology found that margins of at least 0.9 cm were needed to excise 97% of MIS, which is statistically equivalent to thin melanomas 3.
- Another study published in Dermatologic Surgery found that the margins required for clearance were 0.77 ± 0.44 cm (mean ± SD) for invasive melanoma and melanoma in situ treated with mMMS 5.