Overview
Definition
A type of skin cancer that develops from the pigment-producing cells known as melanocytes.
Epidemiology
The deadliest form of skin cancer. Incidence is rising globally, particularly in fair-skinned populations.
Etiology & Risk Factors
- Malignant transformation of melanocytes. Strongly associated with intense, intermittent UV light exposure (sunburns) and genetic mutations (BRAF V600E).
Clinical Symptoms
- ABCDEs of Melanoma: Asymmetry, Border irregularity, Color variation, Diameter > 6mm, Evolving (changing in size, shape, or color)
- Pruritus, bleeding, or ulceration of a mole
Clinical Approach
Diagnosis
- Dermatoscopy: Evaluates pigment patterns
- Excisional Biopsy (Gold Standard): Remove the entire lesion with 1-2mm margins. DO NOT perform a shave biopsy for suspected melanoma (it ruins the Breslow depth measurement).
- Breslow Depth: The most important prognostic factor (measures tumor thickness in millimeters)
Management
- Wide Local Excision: Margins depend on Breslow depth (e.g., 1cm margin for < 1mm depth)
- Sentinel Lymph Node Biopsy (SLNB): Indicated for tumors > 0.8mm thick or if ulcerated
- Advanced Disease: Targeted therapy (BRAF inhibitors like Vemurafenib), Immunotherapy (Anti-PD-1 like Pembrolizumab, Anti-CTLA-4 like Ipilimumab)
Complications
- Metastasis (commonly to the brain, lungs, liver, and bone)
- High mortality if detected late