A 65-year-old patient presents with the following lesion on his trunk. 

As the dermatologist, you astutely biopsy the lesion and pathology shows malignant melanoma with a Breslow depth of 1.2mm without ulceration. The remainder of the synopsis report is non-contributory.

Which of the following is the most appropriate next step in management?

A. Wide local excision with 2cm margins

B. Mohs micrographic surgery

C. Wide local excision with 1.5cm margins and sentinel lymph node biopsy

D. Wide local excision with 1.5cm margins and adjuvant immunotherapy

Rationale: Appropriate recognition and diagnosis of melanoma is a critical first step. It is also important to understand that determining the next step in management, including when and where to place the referral, plays an important role in the appropriate staging and long-term management of each patient. In general, surgeons should take a margin of 0.5cm-1cm for melanoma in situ, 1cm margin for melanoma less than 1mm in depth, 1-2cm margin for melanoma 1-2mm in depth, and 2cm for any melanoma greater than 2mm in depth. 

Correct answer: C. Wide local excision with 1.5cm margins and sentinel lymph node biopsy

A tumor size of 1.2mm without ulceration places the patient at T2a classification. At this depth, the surgeon should take 1-2cm margins around the lesion for their wide local excision. For patients with T2a disease, a sentinel lymph node biopsy is recommended; this helps stage the patient and determine whether adjuvant therapy, monitoring, or lymph node dissection (less often performed in today's time) should be performed. 

Incorrect answers:

A. Wide local excision with 2cm margins. Although 2cm would fall within the 1-2cm range for margins for a melanoma with a depth of 1.2mm, this answer choice does not include performing a lymph node biopsy which is a critical step in staging. The difference in the clinical stage of melanoma varies greatly from stage IA (no lymph node) to stage IIIB (positive lymph node) for a tumor with the same Breslow depth of 1.2mm. 

B. Mohs micrographic surgery. Although still controversial, Mohs surgery is increasingly utilized for some invasive melanomas in addition to melanoma in situ. However, similar to answer choice A this answer omits the use of sentinel lymph node biopsy which would be an important prognostic marker in this patient. Additionally, some may argue that the tissue-sparing benefit of Mohs surgery may not be as critical for a lesion on the trunk as in this patient. 

D. Wide local excision with 1.5cm margins and adjuvant immunotherapy. Adjuvant immunotherapy is not yet indicated for this stage of melanoma unless the patient were to have a positive sentinel lymph node. Patients with tumors that are T3b (Breslow depth 2-4cm with ulceration) would automatically place them into at least stage IIB and these patients could benefit from adjuvant therapy whether or not a sentinel node is positive. 

Additional reading at Fitzpatrick's Dermatology Chapter 116: Melanoma

1. NCCN Guidelines 2024. https://www.nccn.org/professionals/physician_gls/pdf/cutaneous_melanoma.pdf

2. https://www.curemelanoma.org/about-melanoma/melanoma-staging/understanding-melanoma-staging