# Malignant Melanoma (흑색종) --- ## 1. Definition - **Malignant melanoma (흑색종)** is a **malignant tumor of melanocytes**. - Accounts for ~5% of all skin cancers but causes **~75% of skin cancer deaths**. - Aggressive, with potential for local invasion, lymphatic and hematogenous spread. --- ## 2. Epidemiology - Increasing incidence worldwide. - More common in fair-skinned populations (Fitzpatrick I–II). - Median age: 50s, but can occur in young adults. - In Korea/Asia: higher proportion of acral lentiginous melanoma (손발바닥, 손발톱 밑) compared to Western populations. --- ## 3. Risk Factors - **UV exposure**: especially intermittent, intense sunburns. - **Phenotypic**: fair skin, red/blonde hair, light eyes, numerous nevi (>50). - **Genetic**: CDKN2A, CDK4 mutations, family history of melanoma. - **Precursor lesions**: dysplastic nevi, congenital giant nevi. - **Immunosuppression** (e.g., organ transplant). --- ## 4. Clinical Features ### A. Classic Warning Signs (ABCDE Rule) - **A**symmetry - **B**order irregularity - **C**olor variegation (brown, black, red, white, blue) - **D**iameter >6 mm - **E**volution (any change in size, shape, color, or new symptoms like bleeding/itching) ### B. Subtypes (Histologic/Clinical) 1. **Superficial Spreading Melanoma (표재확산 흑색종)** - Most common (~70%). - Irregular macules/patches, slow radial growth. 2. **Nodular Melanoma (결절성 흑색종)** - ~15–20%. - Rapid vertical growth, often black-blue nodule, ulcerates early. - Worst prognosis. 3. **Lentigo Maligna Melanoma (일광흑자 흑색종)** - Elderly, chronically sun-exposed skin (face). - Evolves from lentigo maligna (Hutchinson’s melanotic freckle). 4. **Acral Lentiginous Melanoma (사지말단 흑색종)** - Palms, soles, subungual (손발톱 밑). - Most common type in Asians and Africans. - Often diagnosed late → poor prognosis. --- ## 5. Histopathology - Atypical melanocytes with: - Pagetoid spread (epidermal upward migration). - Lack of maturation with depth. - Dermal invasion, mitotic figures. - Subtype differences: - Superficial spreading: pagetoid scatter. - Nodular: vertical growth phase predominates. - Acral lentiginous: lentiginous proliferation along basal layer. --- ## 6. Staging & Prognosis ### A. Breslow Thickness (가장 중요한 예후인자) - Depth of invasion from granular layer to deepest tumor cell. - <1 mm → excellent prognosis. - > 4 mm → poor prognosis. ### B. Clark Level (역사적, 덜 중요) - Anatomic level of invasion (I–V). ### C. AJCC TNM Staging - Incorporates thickness, ulceration, lymph node status, metastasis. --- ## 7. Management ### A. Primary Treatment = Surgical Excision - Wide local excision with margins based on Breslow thickness: - In situ → 0.5–1 cm margin - <1 mm → 1 cm - 1–2 mm → 1–2 cm - > 2 mm → 2 cm ### B. Sentinel Lymph Node Biopsy (SLNB) - Indicated if Breslow ≥1 mm or high-risk features. - Guides prognosis and management. ### C. Advanced Disease - **Immunotherapy**: PD-1 inhibitors (nivolumab, pembrolizumab), CTLA-4 inhibitors (ipilimumab). - **Targeted therapy**: BRAF inhibitors (vemurafenib, dabrafenib) ± MEK inhibitors (trametinib) in BRAF-mutated tumors. - **Radiotherapy**: limited role, mostly palliative. --- ## 8. Prognosis - Early-stage melanoma (in situ, <1 mm) → >95% 5-year survival. - Metastatic melanoma (Stage IV) → historically <20% 5-year survival, but immunotherapy has dramatically improved outcomes. --- ## 9. Clinical Pearls 1. **Melanoma can mimic benign pigmented lesions** (nevus, seborrheic keratosis, PIH) → dermoscopy is critical. 2. **ABCDE + “Ugly Duckling Sign”**: one mole that looks different from the rest should raise suspicion. 3. **Never laser or destroy a pigmented lesion unless benignity is certain** → histology must be preserved. 4. In Asian patients, **acral/subungual lesions** deserve special vigilance (often diagnosed late). 5. **Breslow thickness is the single most important prognostic factor.** --- ✅ **Summary for practice:** Malignant melanoma (흑색종) is an aggressive melanocytic malignancy with rising incidence. Early detection via ABCDE/dermoscopy and excision with histology is life-saving. Subtype recognition is critical (acral lentiginous in Asians). Prognosis hinges on Breslow thickness. Immunotherapy and targeted therapy have transformed advanced melanoma treatment. ---