Traditional Mohs surgery removes a skin cancer in stages, mapping and examining each layer under a microscope until the margins are clear. For melanoma, identifying abnormal melanocytes on frozen Mohs sections can be challenging with routine staining alone, so many Mohs surgeons use melanocytic immunostains (most commonly MART-1, and in selected situations SOX10 or MITF) to highlight melanoma cells and improve margin assessment.

National dermatology guidelines recognize that Mohs micrographic surgery and other staged excision methods can be appropriate for melanoma in situ, particularly the lentigo maligna subtype, because they allow comprehensive peripheral margin evaluation and tissue-sparing treatment in anatomically constrained sites.

Not every melanoma is best treated with Mohs. Standard wide local excision remains the most common surgical approach for many melanomas. However, Mohs surgery with immunostains is often considered when meticulous margin control and tissue conservation matter most, such as:

• Melanoma in situ (including lentigo maligna) on the face, scalp, ears, or other high-visibility areas
• Large, poorly defined, or recurrent melanoma in situ where margins may extend beyond what is visible
• Selected thin invasive melanomas in specific scenarios when the care team determines margin-controlled surgery is appropriate
• Sites where preserving normal tissue may improve functional or cosmetic outcomes (nose, eyelids, lips, ears)

Clinical literature and guideline discussions emphasize the role of staged, complete circumferential margin assessment techniques (including Mohs) for lentigo maligna and certain thin melanomas in appropriate settings.

Mohs surgery for melanoma is typically performed in stages during a single visit, similar to standard Mohs:

1. Consultation and site confirmation – The surgeon confirms the biopsy-proven diagnosis, reviews the planned approach, and answers questions about likely repair options and recovery.
2. Local anesthesia and first stage removal – The visible lesion is removed along with a thin layer of surrounding tissue. The removed tissue is carefully mapped and color-coded so any remaining tumor can be pinpointed precisely (a core feature of Mohs surgery). (Peak Skin Center)
3. On-site laboratory processing with immunostains – The tissue is processed into microscope slides. For melanoma cases, immunostains (often MART-1; sometimes SOX10 or MITF depending on the clinical/pathology context) are used to highlight melanocytes so the surgeon can more confidently evaluate margins. The tissue processing time for melanoma specimens is significantly longer than for basal cell carcinoma or squamous cell carcinoma.
4. Microscopic margin evaluation and additional stages if needed – If tumor is present at the edge, another thin layer is removed only where the map shows residual cancer. Stages repeat until margins are clear, minimizing unnecessary removal of healthy tissue.
5. Repair once clear – After clearance, the wound is either closed the same day or bandaged with a plan for the most appropriate reconstruction (linear closure, flap, graft, or healing naturally), depending on size and location.

Immunostaining is used because melanoma cells can be subtle on frozen sections. Melanocytic stains can improve visualization of atypical melanocytes at the periphery of the tumor helping the surgeon determine whether margins are truly clear during surgery.

Published outcomes support low local recurrence rates for melanoma in situ and even selected invasive melanomas treated with Mohs using MART-1 immunostaining, and multiple large series describe durable results when the technique and tissue processing are optimized.

Reconstruction depends on the final defect size and location after margins are cleared. Many wounds can be repaired in a straight-line closure. Others, especially on the nose, eyelids, lips, or ears, may require a flap or graft to restore contour and function. In certain situations, a temporary bandage and planned follow-up repair may be recommended when that approach best supports healing and cosmetic outcome. Peak Skin Center also provides guidance on reconstruction options as part of Mohs planning.