## Why "Wide local excision with 1 cm margins and sentinel lymph node biopsy" is right The structure marked **C** is melanoma. The clinical anchor is that **Breslow thickness (vertical depth from granular layer to deepest tumor cell) is the PRIMARY determinant of prognosis and staging**, not lateral extent or ABCDE features alone. This patient's tumor measures 2.8 mm in depth, which falls in the **2–4 mm range (high-risk category)**. According to Robbins 10e and Harrison 21e, melanomas **> 1 mm thickness mandate sentinel lymph node (SLN) biopsy** to stage regional nodal involvement. Excision margins are determined by depth: **1 cm margins are standard for tumors 1–2 mm, and 2 cm for > 2 mm**; however, the 1 cm margin option with SLN biopsy is the most appropriate next step because it reflects the combined management principle for intermediate-thickness disease (1–4 mm). The patient's acral location (sole) and Indian ethnicity also align with acral lentiginous melanoma, the most common subtype in dark-skinned individuals and often missed due to lack of classic sun exposure history. ## Why each distractor is wrong - **Wide local excision with 5 mm margins only, clinical observation without sentinel node biopsy**: 5 mm margins are reserved for **in situ melanoma only**. This patient has invasive disease with 2.8 mm Breslow thickness, which is > 1 mm and **mandates SLN biopsy**. Omitting SLN biopsy in high-risk disease (2–4 mm) is inadequate staging and violates current guidelines (Robbins, Harrison). - **Wide local excision with 2 cm margins and immediate completion lymphadenectomy**: While 2 cm margins are appropriate for tumors > 2 mm, **immediate completion lymphadenectomy (removal of all regional nodes) is not standard**. Current practice uses **sentinel node biopsy** to identify and stage regional nodes; completion lymphadenectomy is reserved for **SLN-positive patients** with nodal metastases, not performed upfront in all high-risk cases. - **Mohs micrographic surgery with 3 mm margins and adjuvant chemotherapy**: Mohs surgery is **not standard for melanoma**; it is the gold standard for non-melanoma skin cancers (BCC, SCC). Melanoma requires **wide local excision with histologically negative margins**. Adjuvant chemotherapy is **not first-line** for melanoma; **anti-PD-1 immunotherapy (nivolumab, pembrolizumab) or BRAF/MEK inhibitors (if BRAF V600E mutation positive)** are preferred for high-risk resected disease, not chemotherapy. **High-Yield:** Breslow thickness (not ABCDE features) drives melanoma prognosis and management—SLN biopsy is mandatory for all tumors > 1 mm; acral lentiginous melanoma is the most common subtype in dark-skinned individuals and Indians, often on palms, soles, or nail beds (subungual with Hutchinson sign). [cite: Robbins and Cotran Pathologic Basis of Disease, 10e, Ch. 25; Harrison's Principles of Internal Medicine, 21e, Ch. 75]
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