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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- Prognosis correlates with Breslow thickness (depth of invasion in mm)
- ABCDE: Asymmetry, Border irregularity, Colour variation, Diameter >6 mm, Evolving
- Subtypes: superficial spreading (~70%), nodular (worst prognosis), lentigo maligna, acral lentiginous
- Excision biopsy with 2 mm margin for diagnosis (NEVER punch biopsy). Then WLE based on Breslow
- SLNB for staging if Breslow >=0.8 mm. Immunotherapy for advanced disease
Overview
Malignant melanoma is aggressive cancer arising from melanocytes. Accounts for ~4% of skin cancers but causes the majority of skin cancer deaths. Prognosis primarily determined by Breslow thickness. Major subtypes: superficial spreading (~70%), nodular (~15%, worst prognosis), lentigo maligna (~10%), acral lentiginous (~5%, commonest in dark-skinned individuals). Risk factors: UV exposure (intermittent intense exposure/sunburn), fair skin, multiple naevi, dysplastic naevi, family history.
Epidemiology
Over 16,000 new cases and ~2,300 deaths/year in the UK. Incidence increased ~45% over past decade. More common in women (legs) than men (trunk). Five-year survival >95% for stage I but <20% for stage IV without treatment. One of the most common cancers in young adults.
Clinical Features
Symptoms
New pigmented lesion or change in existing mole (size, shape, colour)
ABCDE criteria: Asymmetry, Border, Colour, Diameter, Evolving
Itching, bleeding, or crusting of a mole
Dark streak under fingernail/toenail (subungual melanoma)
Rapidly growing dark nodule (nodular melanoma)
Amelanotic (non-pigmented) growing nodule
Signs
Asymmetric pigmented lesion with irregular borders and colour variation
Superficial spreading: irregular flat lesion with variable pigmentation
Nodular melanoma: rapidly growing, raised, uniformly dark nodule
Lentigo maligna: slowly expanding brown macule on sun-damaged facial skin
Acral lentiginous: pigmented lesion on palm, sole, or nail bed (Hutchinson's sign = nail fold pigmentation)
Regional lymphadenopathy
Investigations
First-line
DermoscopyAtypical pigment network, irregular dots/globules, blue-white veil
Excision biopsyGOLD STANDARD — excise with 2 mm margin. Do NOT punch biopsy
Second-line
HistopathologyBreslow thickness, ulceration status, mitotic rate, margins
Sentinel lymph node biopsyFor staging if Breslow >=0.8 mm. Prognostic, not proven to improve survival
Specialist
BRAF mutation testingGuides targeted therapy in stage III/IV
CT chest/abdomen/pelvis, CT/MRI brainStaging for stage III/IV
Vitamin D levelMeasure at diagnosis — correct deficiency
1
Referral
- Two-week wait for any suspicious pigmented lesion meeting ABCDE criteria
2
Excision biopsy
- Excise entire lesion with 2 mm clinical margin — NEVER punch biopsy
3
Wide local excision (definitive)
- Breslow <1 mm: 1 cm margin
- Breslow 1-2 mm: 1-2 cm margin
- Breslow 2.1-4 mm: 2-3 cm margin
- Breslow >4 mm: 3 cm margin
- SLNB if Breslow >=0.8 mm
4
Adjuvant and systemic therapy (stage III/IV)
- Adjuvant immunotherapy: nivolumab or pembrolizumab for resected stage III
- Adjuvant targeted: dabrafenib + trametinib (BRAF-mutant stage III)
- Metastatic: checkpoint inhibitors or BRAF/MEK inhibitors
5
Follow-up
- Stage IA: self-monitoring, discharge after excision
- Stage IB-IIC: clinical review for 5 years
- Sun protection and skin self-examination education
Complications
- Metastasis: Lymphatic and haematogenous (lung, liver, brain, bone). Brain metastases common
- Local recurrence: At or near excision site
- In-transit metastases: Cutaneous nodules between primary and regional nodes
- Second primary melanoma: ~5-8% lifetime risk
UKMLA Exam Tips
- 1Breslow thickness is THE most important prognostic factor
- 2NEVER punch biopsy a suspected melanoma — always excision biopsy
- 3Nodular melanoma: rapid vertical growth, worst prognosis
- 4Hutchinson's sign: periungual pigment extending to nail fold = subungual melanoma
- 5Superficial spreading is the commonest subtype (~70%)
- 6Acral lentiginous: not UV-related, commonest in dark-skinned individuals
- 7ABCDE criteria: Asymmetry, Border, Colour, Diameter, Evolving
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