Definition
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Malignant melanoma: aggressive melanocyte-derived skin cancer with high potential for metastasis.
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Most serious form of skin cancer; early detection is crucial.
Epidemiology & Risk Factors
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Accounts for ~1–2% of skin cancers but majority of skin cancer deaths.
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Peak incidence: 50–60 years.
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Risk factors:
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UV exposure (especially intermittent, severe sunburns in childhood)
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Fair skin, light hair, blue/green eyes
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Multiple or atypical nevi
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Family history of melanoma
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Immunosuppression
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Clinical Features
ABCDE Criteria (high-yield for recognition)
| Letter | Feature | Significance |
|---|---|---|
| A | Asymmetry | One half unlike the other |
| B | Border | Irregular, notched, poorly defined |
| C | Colour | Variegated (brown, black, red, white, blue) |
| D | Diameter | >6 mm (pencil eraser size) |
| E | Evolution | Change in size, shape, colour, or symptoms |
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Common sites: back in men, legs in women, then face, neck, arms.
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May present as new mole, changing existing mole, or pigmented lesion.
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Symptoms: itching, bleeding, ulceration in advanced lesions.
💡 PLAB Tip: Any changing pigmented lesion warrants urgent assessment.
Types of Melanoma
| Type | Characteristics | Common Location |
|---|---|---|
| Superficial spreading | Most common (~70%), slow radial growth | Trunk, limbs |
| Nodular | Rapid vertical growth, often dark blue/black | Any site |
| Lentigo maligna | Slowly enlarging, sun-damaged skin, elderly | Face, neck |
| Acral lentiginous | Palms, soles, nail beds; more common in darker skin | Acral sites |
Investigations
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Dermoscopy for suspicious lesions.
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Excisional biopsy (full-thickness preferred) – gold standard.
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Staging: Breslow thickness, Clark level, sentinel lymph node biopsy if >1 mm depth.
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Imaging (CT, PET, MRI) for suspected metastasis.
Management
Surgical
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Wide local excision with margins based on Breslow thickness.
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Sentinel lymph node biopsy for intermediate/high-risk lesions.
Systemic Therapy (advanced/metastatic)
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Immunotherapy: checkpoint inhibitors (nivolumab, pembrolizumab).
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Targeted therapy: BRAF/MEK inhibitors for BRAF-mutated melanoma.
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Adjuvant therapy for high-risk resected melanoma.
Follow-Up
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Regular skin checks, patient education on sun protection.
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Self-examination and monitoring for new or changing lesions.
Complications
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Local recurrence
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Regional lymph node metastasis
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Distant metastasis: lung, liver, brain, bone
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Poor prognosis in nodular or metastatic melanoma
PLAB-Style Questions
Q1: A 55-year-old man presents with a 7 mm asymmetrical, irregularly pigmented lesion on his back that has grown over 3 months. Best next step?
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A. Reassure and monitor
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B. Shave biopsy
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C. Excisional biopsy
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D. Topical therapy
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E. Cryotherapy
✅ Answer: C. Excisional biopsy
(Suspicious lesion with ABCDE features → excisional biopsy is gold standard.)
Q2: Which of the following features is most associated with poor prognosis in melanoma?
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A. Superficial spreading type
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B. Breslow thickness >4 mm
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C. Lentigo maligna
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D. Lesion on forearm
✅ Answer: B. Breslow thickness >4 mm
(Thickness correlates strongly with risk of metastasis.)
High-Yield Pearls
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ABCDE criteria = essential for lesion assessment.
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Early excisional biopsy = key for diagnosis.
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Breslow thickness predicts prognosis.
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Nodular melanoma = rapid vertical growth → worse prognosis.
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Sun protection is vital for prevention; patients with multiple nevi need surveillance.
Next dermatology topic could naturally be Basal Cell Carcinoma vs Squamous Cell Carcinoma, which frequently appear in exam vignettes and help contrast melanoma vs non-melanoma skin cancers.
