What do images of melanoma look like and how is it diagnosed and treated?

Melanoma: Visual Characteristics, Diagnosis, and Treatment

What Melanoma Looks Like

Melanoma presents as pigmented lesions characterized by the ABCDE criteria: Asymmetry, Border irregularity, Color heterogeneity, Diameter (though many are now <5mm), and Evolution (changes in color, elevation, or size). 1, 2 While melanomas are typically darkly pigmented, they can be amelanotic (non-pigmented), making clinical recognition more challenging. 3

Key Visual Features to Identify:

• Asymmetry: One half of the lesion does not match the other half 2
• Border irregularity: Edges are ragged, notched, or blurred 1, 2
• Color heterogeneity: Multiple colors or uneven distribution of pigment within the lesion 1, 2
• Diameter: Historically >6mm, but many primary melanomas now present at <5mm 1
• Evolution: Any change in size, shape, color, elevation, or new symptoms like bleeding or itching 2

Additional Clinical Signs:

• Look for the "ugly duckling" sign—a lesion that stands out as different from the patient's other nevi 4
• Examine for tumor satellites, in-transit metastases, and regional lymph node enlargement 1
• Check for multiple suspicious pigmented lesions, as 8% of melanoma patients develop a secondary melanoma within 2 years 1

Diagnostic Approach

Full-thickness excisional biopsy with a 2-5mm margin of normal skin and a cuff of subdermal fat is the only acceptable diagnostic approach for suspected melanoma. 2 This technique allows accurate Breslow thickness measurement, which is critical for staging and prognosis. 2

Mandatory Biopsy Requirements:

• Include deep reticular dermis and subcutaneous fat 2
• Avoid shave biopsies or punch biopsies that may not capture full tumor depth 2
• Process specimens at an experienced pathology institute following WHO classification 1

Essential Histopathology Report Elements:

• Breslow thickness in millimeters (most important prognostic factor) 1, 2
• Clark level of invasion (I-V) 1
• Presence of ulceration (upstages the tumor) 1
• Mitotic rate (especially critical for pT1 lesions) 1
• Presence and extent of regression 1, 4
• Surgical margin clearance status 1, 2
• Histological type and special variants 2

Staging Workup by Risk Level:

Low-risk melanomas (tumor thickness <1mm or pT1a):

• Physical examination only—no imaging required 1, 5
• Complete skin examination and lymph node palpation 2

Higher-risk melanomas (≥1mm thickness or stages IIB and above):

• CT chest/abdomen/pelvis to detect visceral metastases 5
• Brain MRI for cerebral metastases 5
• Consider PET-CT for advanced stage III disease 5
• Ultrasound of regional lymph node basins 1

Critical caveat: Routine imaging in high-risk patients may detect recurrences earlier but has not demonstrated survival benefit and carries high false-positive rates. 1, 5 Imaging should be reserved for symptomatic patients or when determining extent of disease before treatment. 5

Treatment Algorithm

Primary Melanoma (Stages 0-II):

Wide local excision with margins determined by Breslow thickness:

• In situ melanoma: 0.5cm margins 1
• ≤2mm thickness: 1cm margins 1
• >2mm thickness: 2cm margins 1

Sentinel lymph node biopsy (SLNB):

• Recommended for tumors >1mm thickness and/or ulceration for accurate staging 1
• Consider for pT1b tumors >0.75mm 1
• Provides prognostic information but does not improve overall survival 1
• Should only be performed by experienced teams 1

Stage III (Regional Metastases):

Surgical management:

• Complete lymph node dissection if sentinel node positive (though survival benefit unproven) 1
• R0 resection (complete removal with negative margins) for isolated locoregional recurrences 1

Adjuvant therapy for resected stage III:

• Evaluate all patients for adjuvant interferon therapy 1
• Patients with microscopic nodal involvement and/or ulcerated primaries most likely to benefit 1
• For stage IIIB and higher, prioritize enrollment in clinical trials 1

Stage IV (Metastatic Disease):

First priority: BRAF mutation testing on metastasis or primary tumor 1

First-line systemic therapy (most recent guideline 2015):

• Anti-PD1 antibodies (pembrolizumab, nivolumab) for all patients 1
• BRAF/MEK inhibitor combinations for BRAF-mutant melanoma 1
• Ipilimumab (anti-CTLA4 antibody) as alternative 1

Surgical options:

• Consider resection or stereotactic irradiation of isolated metastases in fit patients with good performance status 1
• Goal is R0 resection 1

Palliative radiotherapy:

• Indicated for symptomatic brain metastases 1
• Indicated for painful bone metastases 1

If newer therapies unavailable:

• Dacarbazine or temozolomide (modest activity only) 1

Critical management principle: Stage IV patients require interdisciplinary tumor board discussion at centers with melanoma expertise. 1

Follow-Up and Surveillance

Patient education priorities:

• Avoid sunburns and extended unprotected UV exposure (solar and artificial) 1
• Perform lifelong monthly self-examinations of skin and lymph nodes 1
• Family members have increased melanoma risk and need counseling 1

Surveillance schedule (no definitive consensus exists):

• Traditional approach: Every 3 months for first 3 years, then every 6-12 months 1
• Important caveat: Most relapses are detected by patients themselves, questioning the cost-effectiveness of frequent visits 1
• Tailor intervals to individual risk profile 1

Imaging surveillance:

• Not indicated for thin melanomas (<1mm) 1, 5
• May consider for high-risk patients (thick primaries, prior metastases): ultrasound of lymph nodes, CT, or PET-CT every 3-6 months for 2-5 years 1, 5
• No survival benefit demonstrated from routine imaging 1, 5

Blood tests:

• S-100 has higher specificity than LDH for disease progression if any blood test used 1
• Routine blood tests not strongly recommended 1

Common Pitfalls to Avoid:

• Do not perform shave or inadequate punch biopsies on suspected melanomas—always full-thickness excision 2
• Do not delay referral to experienced centers for suspicious lesions 2
• Do not order routine imaging for low-risk melanomas—it increases false positives without survival benefit 1, 5
• Do not forget that 35% of lentigo maligna melanoma patients develop another cutaneous malignancy within 5 years 1
• Maintain low threshold for biopsy in high-risk populations (prior skin cancer, immunosuppression, genetic syndromes) 2