Introduction to Melanoma and Early Detection

Melanoma represents one of the most aggressive forms of skin cancer, with its incidence rising globally. In Hong Kong, recent data from the Hong Kong Cancer Registry shows approximately 1,200 new melanoma cases diagnosed annually, with mortality rates increasing by 3.2% per year over the past decade. Early detection becomes paramount when considering that melanoma diagnosed at stage I has a 5-year survival rate exceeding 98%, while stage IV melanoma survival drops dramatically to below 25%. The visual nature of skin lesions makes dermatological examination particularly crucial for early intervention.

The evolution of dermoscopy has revolutionized melanoma diagnosis, providing clinicians with a powerful tool for non-invasive examination of skin lesions. Modern dermatoscope uses include polarized and non-polarized light systems that enable visualization of subsurface skin structures invisible to the naked eye. Studies from Queen Mary Hospital in Hong Kong demonstrate that dermoscopy improves diagnostic accuracy for melanoma by 20-30% compared to naked-eye examination alone. The technique allows dermatologists to examine specific morphological features including pigment networks, vascular patterns, and specific structural elements that differentiate malignant from benign lesions.

Understanding dermoscopy images of melanoma requires recognizing that this imaging technique bridges the gap between clinical dermatology and histopathology. The dermatoscope essentially functions as a skin surface microscope, typically providing 10x to 70x magnification. Contemporary devices often incorporate digital imaging capabilities, allowing for sequential monitoring of suspicious lesions over time. The importance of this technology extends beyond diagnosis to include documentation, patient education, and surgical planning. In Hong Kong's public healthcare system, dermoscopy has become standard practice in dermatology clinics, with approximately 85% of dermatologists routinely using the technique for pigmented lesion evaluation.

Key Dermoscopic Features of Melanoma

Asymmetry represents one of the most critical dermoscopic criteria for melanoma identification. Unlike benign lesions that typically exhibit symmetrical growth patterns, melanomas often demonstrate structural asymmetry across multiple axes. When evaluating dermoscopy images of melanoma, clinicians assess asymmetry in three dimensions: pattern distribution, color distribution, and structural organization. Border irregularity manifests as uneven, angulated, or notched margins with abrupt termination of pigment networks. Research from the Chinese University of Hong Kong indicates that combining asymmetry and border assessment achieves 89% sensitivity for melanoma detection.

Color variation provides crucial diagnostic information in melanoma evaluation. Malignant lesions typically display three or more colors, with specific hues carrying diagnostic significance:

• Dark brown to black: indicates concentrated melanin presence
• Blue-gray: suggests melanin in deeper dermal layers
• White: represents regression or fibrosis
• Red: demonstrates vascular proliferation or inflammation

The presence of blue-white structures over raised areas particularly suggests invasive melanoma. Pattern analysis reveals distinctive organizational structures in melanocytic lesions. The reticular pattern appears as a grid-like network commonly seen in benign nevi but becomes irregular and disrupted in melanoma. The globular pattern features round to oval structures representing nests of melanocytes, while the starburst pattern shows radial projections at the periphery, typically associated with rapidly growing lesions. Understanding these patterns requires comparing dermoscopy of squamous cell carcinoma, which typically shows different vascular patterns and scale characteristics.

Interpreting Dermoscopy Images: A Step-by-Step Approach

Systematic evaluation of dermoscopy images begins with pigment network assessment. A typical benign network appears as a uniform honeycomb-like structure with thin lines and regular distribution. In melanoma, the network becomes atypical with broadened lines, irregular holes, and abrupt peripheral termination. Network breakdown areas often indicate malignant transformation. Additional features include branched streaks and pseudopods—bulbous projections at the lesion periphery that suggest radial growth phase. Hong Kong dermatology protocols recommend using the 3-point checklist which includes atypical network as a major criterion.

Vascular structure analysis provides critical diagnostic information, particularly for non-pigmented or hypopigmented melanomas. Common vascular patterns in melanoma include:

Specific dermoscopic clues provide additional diagnostic certainty. The blue-white veil appears as an irregular, structureless blue-to-white pigmentation overlying raised areas, indicating compact orthokeratosis and melanin in the dermis. Pseudopods represent finger-like projections at the lesion border with bulbous ends, suggesting confluent radial growth. Comparing these features with dermoscopy of squamous cell carcinoma reveals important differences—SCC typically shows keratin masses, blood spots, and white structureless areas rather than the melanin-specific patterns seen in melanoma.

Common Dermoscopic Patterns in Melanoma: Detailed Examples

Superficial spreading melanoma, representing approximately 70% of all melanomas, demonstrates distinctive dermoscopic features. Early lesions typically show an atypical pigment network with irregular holes and thickened lines. As the lesion progresses, multiple colors emerge including dark brown, blue-gray, and red. Specific features include:

• Multiple brown dots clustered irregularly throughout the lesion
• Radial streaming and pseudopods at the periphery
• Blue-white veil over raised portions
• Regression structures including white scar-like areas and blue-gray peppering

Nodular melanoma presents different challenges in dermoscopic evaluation. These lesions often lack the classic ABCD features and instead present as symmetrical, elevated nodules. Dermoscopy reveals:

• Polymorphous vascular pattern with dotted and linear irregular vessels
• Blue-black color with structureless areas
• Ulceration appearing as red structureless areas
• Multiple milky-red globules

Lentigo maligna melanoma, commonly occurring on sun-damaged skin of elderly patients, shows distinctive patterns under dermoscopy. Early lesions demonstrate asymmetrical pigmented follicular openings and annular-granular patterns. Advanced lesions develop dark rhomboidal structures and slate-gray dots surrounding hair follicles. Case studies from Hong Kong dermatology practices illustrate how these patterns manifest differently across skin types, with pigmentation often more subtle in Asian patients compared to Caucasian patients.

Potential Pitfalls and Challenges in Dermoscopy Interpretation

Several benign conditions can mimic melanoma dermoscopically, creating diagnostic challenges. These melanoma mimics include:

• Regressing nevi showing blue-white areas and peppering
• Spitz nevi with starburst patterns and symmetrical distribution
• Pigmented basal cell carcinoma showing leaf-like areas and large blue-gray ovoid nests
• Seborrheic keratosis with milia-like cysts and comedo-like openings

Differentiating these conditions requires understanding subtle differences in pattern recognition. For instance, while both melanoma and Spitz nevi may show starburst patterns, melanoma typically demonstrates asymmetry and pattern disorder absent in benign Spitz nevi. Similarly, comparing dermoscopy of squamous cell carcinoma with melanoma reveals that SCC typically shows keratin masses and blood spots rather than melanin-specific patterns. Vascular patterns also differ significantly, with SCC often showing hairpin vessels and glomerular vessels rather than the polymorphous vessels of melanoma.

Improving dermoscopy skills requires structured training and continuous practice. Hong Kong dermatology training programs now incorporate mandatory dermoscopy modules with minimum 50 supervised cases. Additional resources include:

• Online databases with annotated dermoscopy images of melanoma
• Structured algorithms like the 7-point checklist and ABCD rule of dermoscopy
• Regular participation in dermatoscopy conferences and workshops
• Use of teledermatology platforms for second opinions

Emphasizing the Role of Dermoscopy in Melanoma Management

The integration of dermoscopy into clinical practice has transformed melanoma management by enabling earlier detection and reducing unnecessary excisions. Studies from Hong Kong show that dermatoscope uses extend beyond diagnosis to include monitoring high-risk patients, with digital dermoscopy allowing comparison of lesions over time. This sequential monitoring is particularly valuable for patients with multiple atypical nevi, where subtle changes might indicate early malignant transformation. The technology also facilitates precise surgical planning by better defining lesion margins preoperatively.

Patient education represents a crucial component of melanoma prevention and early detection. Dermoscopy images serve as powerful visual aids during patient consultations, helping individuals understand concerning features in their skin lesions. Hong Kong dermatology clinics report improved patient compliance with follow-up appointments when dermoscopy is used as an educational tool. Additionally, awareness campaigns incorporating dermoscopic images have proven effective in teaching the public to recognize potentially dangerous lesions, ultimately contributing to earlier presentation and improved outcomes.

The future of dermoscopy lies in technological integration, with artificial intelligence algorithms showing promise in assisting with pattern recognition. Research initiatives at the University of Hong Kong are developing AI systems trained on thousands of dermoscopy images of melanoma to support clinical decision-making. These systems aim to complement rather than replace dermatological expertise, particularly in primary care settings where dermatoscopy experience may be limited. As technology advances, the combination of human expertise and computer-assisted diagnosis will likely further improve melanoma detection rates and patient outcomes.