Melanoma
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Malignant Melanoma is a tumour of melanocytes (pigment-producing cells). It is the most deadly form of skin cancer due to its high potential for metastasis.
Incidence is rising faster than any other major cancer (doubled in last 30 years).
Clinical Scenario: The Ugly Duckling
A 40-year-old man presents with a dark, irregularly shaped mole on his back. He says it 'itches' and has bled once. On inspection, he has many moles, but this one looks completely different from the others.
Key Teaching Points
- The **'Ugly Duckling Sign'** (the outlier lesion) is highly sensitive for melanoma.
- Itching or Bleeding are late signs.
- **Action**: Urgent Referral (2 Week Wait) for Excision Biopsy.
- **Do NOT** perform a punch/shave biopsy (it ruins the Breslow staging).
Image Integration Plan
| Image Type | Source | Status |
|---|---|---|
| Management Algorithm | AI-generated | PENDING |
| Pathophysiology (Vertical Growth) | AI-generated | PENDING |
| Clinical (Superficial Spreading) | Web Source | PENDING |
| Clinical (Acral - Nail) | Web Source | PENDING |
[!NOTE] Image Generation Status: Diagrams illustrating the Breslow Depth measurement are queued.
The ABCDE Rule
- A - Asymmetry: One half doesn't match the other.
- B - Border: Irregular, jagged, or blurred.
- C - Colour: Variegated (shades of tan, brown, black, red, blue).
- D - Diameter: > 6mm (pencil eraser).
- E - Evolution: Changing size/shape/colour (Most sensitive).
- Incidence: 5th most common cancer in UK.
- Risk Factors:
- UV Exposure: Intermittent high-intensity UV (sunburns) is worse than chronic exposure. Sunbeds.
- Phenotype: Fair skin (Type I/II), Red hair, Freckles.
- Naevi: >50 common moles or >5 atypical moles.
- Genetics: CDKN2A mutation.
- Origin: Neural crest-derived melanocytes in the basal layer of epidermis.
- Radial Growth Phase: Spreads horizontally (in-situ). Curable.
- Vertical Growth Phase: Invades deep into dermis. Metastatic potential correlates with Depth (Breslow thickness).
- Mutations: BRAF V600E mutation is present in ~50% (targetable).
Subtypes
- Superficial Spreading (70%): Most common. Flat, irregular. Back (men) or Legs (women).
- Nodular (15%): Rapid vertical growth. Raised black/red lump. Very aggressive.
- Lentigo Maligna: Elderly. Sun-damaged face. Slow growing patch ("Hutchinson's Freckle").
- Acral Lentiginous: Palms, Soles, Nails. Commonest type in Black/Asian populations.
- Hutchinson's Sign: Pigment extending onto the nail fold (cuticle).
- Amelanotic: Pink/Red lesion without pigment. Hard to diagnose.
- Dermoscopy: Essential tool. Look for "atypical network", "blue-white veil", "dots/globules".
- Lymph Nodes: Palpate regional nodes.
- Liver: Hepatomegaly (mets)?
- Excision Biopsy: Standard of Care.
- Complete removal with 2mm margin.
- Avoid incision biopsy (risk of sampling error and seeding).
- Histopathology:
- Breslow Thickness: Depth in mm from granular layer to deepest tumour cell. Key prognostic factor.
- Staging CT/PET: For high-risk disease.
- Genetic Testing: BRAF / NRAS status.
A. Surgical (Wide Local Excision)
Once diagnosis confirmed, a second operation clears a safety margin based on Breslow depth:
- In-situ: 5mm margin.
- < 1mm: 1cm margin.
- 1 - 2mm: 1 - 2cm margin.
- > 2mm: 2cm margin.
B. Sentinel Lymph Node Biopsy (SLNB)
- Offered if Breslow > 1mm (or ulcerated).
- Identifies microscopic spread to the draining node. If positive -> Completion Lymphadenectomy or Adjuvant therapy.
C. Systemic Therapy (Metastatic/Adjuvant)
A revolution in the last decade.
- Immunotherapy (Checkpoint Inhibitors):
- Nivolumab / Pembrolizumab (Anti-PD1).
- Ipilimumab (Anti-CTLA4).
- "Unmasks" the cancer so the immune system kills it. Long-term durable clearance possible.
- Targeted Therapy:
- Vemurafenib / Dabrafenib (BRAF Inhibitors).
- Only if BRAF V600E positive. Rapid response but resistance develops.
- Metastasis: Brain, Liver, Lungs, Bone. (Brain mets are frequent cause of death).
- Lymphoedema: After node clearance.
Depends entirely on Breslow Thickness at presentation.
- < 1mm: >95% 5-year survival.
- > 4mm: <50% 5-year survival.
- NICE NG14: Melanoma: assessment and management.
- AJCC 8th Edition: Staging system.
What is Melanoma? It is a serious skin cancer that starts in the cells that give your skin colour (moles).
What causes it? Most cases are caused by UV damage from the sun or sunbeds. Getting sunburnt, especially as a child, significantly increases the risk later in life.
What should I look for? (ABCDE) Check your moles regularly. Look for one that stands out ("Ugly Duckling").
- Asymmetry (lopsided).
- Border (ragged edges).
- Colour (mixture of brown, black, red, blue).
- Diameter (larger than a pencil top).
- Evolution (Changing).
How is it treated? We cut it out. If we catch it early (thin), a small scar is all you get, and you are cured. If it is deep, we need to take a wider margin of skin and check the glands. For advanced cancer, we now have powerful immune-boosting drugs that can control the disease for a long time.
- NICE. Melanoma: assessment and management [NG14]. 2015.
- Robert C, et al. Pembrolizumab in advanced melanoma. N Engl J Med. 2015.
- Breslow A. Thickness, cross-sectional areas and depth of invasion in the prognosis of cutaneous melanoma. Ann Surg. 1970.