Key Facts

Dermatoscopy (dermoscopy) is an essential tool for primary care assessment of skin lesions. It enables visualisation of structures below the stratum corneum not visible to the naked eye. Training in dermatoscopy significantly improves diagnostic performance.

Epidemiology

• Melanoma: approximately 16,000 new cases/year in UK (5th most common cancer); 2,300 deaths/year
• BCC: approximately 150,000 new cases/year in UK (most common cancer)
• SCC: approximately 50,000 new cases/year in UK
• Non-melanoma skin cancer accounts for >20% of all cancers diagnosed in the UK
• Incidence rising due to UV exposure, ageing population, and increased detection

Principles of Dermatoscopy

• Uses polarised light or contact medium to reduce surface reflection
• Allows visualisation of structures in epidermis, dermoepidermal junction, and papillary dermis
• Structures assessed: pigment network, dots, globules, streaks, blue-white structures, vascular patterns
• Improves sensitivity for melanoma from 60-70% (naked eye) to 80-90% (dermoscopy)

Common Benign Lesions

• Seborrhoeic keratosis: milia-like cysts, comedo-like openings, brain-like pattern
• Dermatofibroma: central white scar-like patch, peripheral pigment network
• Haemangioma: red lacunae (blood-filled spaces)
• Blue naevus: homogeneous blue-grey colour, symmetrical

Melanoma

• Changing mole (size, shape, colour)
• New pigmented lesion (especially after age 40)
• Ugly duckling sign (lesion that looks different from patient's other moles)
• ABCDE criteria: Asymmetry, Border irregularity, Colour variation, Diameter >6mm, Evolving

Basal Cell Carcinoma

• Pearly papule or nodule with rolled edges
• Telangiectasia on surface
• Central ulceration (rodent ulcer)
• Commonly on sun-exposed skin (face, scalp, ears)
• Slow-growing; very rarely metastasises

Squamous Cell Carcinoma

• Keratotic nodule or plaque
• May be ulcerated
• Firm, indurated
• Sun-exposed areas; may arise in actinic keratosis
• Can metastasise (2-5%)

Actinic Keratosis (Pre-malignant)

• Rough, scaly patches on sun-exposed skin
• Risk of progression to SCC: approximately 10% over 10 years

Red Flags (2-Week-Wait Referral — NICE NG12)

• Dermoscopic features suspicious for melanoma
• 7-point checklist score ≥3
• Non-healing skin ulcer >8 weeks
• Lesion growing rapidly
• New lesion in immunosuppressed patient

Bedside

• Full skin examination (total body skin check) in good lighting
• Dermatoscopy of any suspicious lesion
• Photography and documentation
• 7-point weighted checklist assessment

7-Point Weighted Checklist (NICE NG12)

• Major features (2 points each): change in size, irregular shape, irregular colour
• Minor features (1 point each): diameter ≥7mm, inflammation, oozing/crusting, sensory change
• Score ≥3: refer via 2-week-wait pathway

Biopsy

• Excision biopsy: gold standard for suspicious pigmented lesions (complete excision with 2mm clinical margin)
• DO NOT incision biopsy or shave biopsy a suspected melanoma
• Punch biopsy: appropriate for non-pigmented suspicious lesions, dermatological conditions

Special Tests

• Sentinel lymph node biopsy: for melanoma staging (Breslow thickness >1mm)
• CT staging: for advanced melanoma or SCC with suspected metastasis
• Genetic testing: BRAF mutation in melanoma (guides immunotherapy/targeted therapy)

Benign Lesions

• Seborrhoeic keratosis: reassurance; cryotherapy or curettage if symptomatic
• Skin tags: snip excision, cryotherapy
• Actinic keratosis: cryotherapy, topical 5-fluorouracil 5% cream (Efudix) BD for 4 weeks, topical diclofenac 3% gel BD for 8-12 weeks, or topical imiquimod 5% (Aldara)

Melanoma (Specialist-Led)

• Excision margins (based on Breslow thickness):
  • In situ: 5mm margin
  • <1mm: 1cm margin
  • 1-2mm: 1-2cm margin
  • 2-4mm: 2-3cm margin

  • 4mm: 3cm margin

• Sentinel lymph node biopsy if Breslow >1mm
• Adjuvant therapy: immunotherapy (pembrolizumab, nivolumab) for stage III-IV; BRAF inhibitors (dabrafenib + trametinib) if BRAF mutant

BCC

• Surgical excision (3-5mm margin): first-line for most
• Mohs micrographic surgery: for high-risk/recurrent or cosmetically sensitive areas
• Topical imiquimod: for superficial BCC
• Radiotherapy: for inoperable BCC or patient preference

SCC

• Surgical excision (5-10mm margin depending on risk)
• Radiotherapy: adjuvant or primary for inoperable
• Lymph node dissection if metastatic

Referral Criteria

• Suspected melanoma: 2-week-wait dermatology/plastics
• Suspicious non-melanoma skin cancer: 2-week-wait
• Multiple or recurrent BCC: dermatology
• Immunosuppressed patients with skin lesions: lower threshold for referral
• Dermoscopic uncertainty: dermatology opinion (teledermatology if available)

• Melanoma (Breslow thickness): <1mm 5-year survival >95%; 1-2mm 80-90%; 2-4mm 65-75%; >4mm 50-60%
• BCC: cure rate >95% with appropriate excision; metastasis extremely rare (<0.1%)
• SCC: cure rate >90% with excision; metastasis 2-5% overall (higher for lip, ear, immunosuppressed)
• Actinic keratosis: progression to SCC approximately 0.5-1% per lesion per year (10% cumulative over 10 years)
• Melanoma stage at diagnosis is the strongest predictor of survival: early detection through dermatoscopy and screening is key
• Dermatoscopy training: reduces unnecessary referrals by 30% while maintaining sensitivity for melanoma

7-Point Weighted Checklist

Score ≥3 = 2-week-wait referral

Melanoma Breslow Thickness and Excision Margins