I. Introduction: The Importance of Early Melanoma Detection

Melanoma, the most aggressive form of skin cancer, accounts for a significant portion of skin cancer-related deaths worldwide. In Hong Kong, the incidence of melanoma has been steadily rising, with approximately 200 new cases reported annually. Early detection is crucial, as the 5-year survival rate drops from 99% for localized melanoma to just 25% for metastatic disease. Dermoscopy, a non-invasive diagnostic tool, has revolutionized early melanoma detection by allowing dermatologists to visualize subsurface structures not visible to the naked eye.

The role of dermoscopy in early detection cannot be overstated. Studies have shown that dermoscopy improves diagnostic accuracy by 20-30% compared to clinical examination alone. A dermatoscope with UV light further enhances this capability by revealing subtle pigmentation patterns and vascular structures. For dermatologists, mastering dermoscopic interpretation is essential, particularly when dealing with early melanomas that may lack classic clinical features.

Modern dermoscope for dermatologist devices combine polarized and non-polarized light with advanced magnification (typically 10x), enabling detailed examination of dermoscopic features. This technology has become the standard of care in pigmented lesion evaluation, particularly in high-risk populations and regions with increasing melanoma incidence like Hong Kong.

II. Dermoscopic Criteria for Melanoma Diagnosis

The systematic evaluation of pigmented lesions using dermoscopy relies on established diagnostic criteria. These are typically divided into major and minor criteria, with major features carrying greater diagnostic weight. The most significant major criteria include atypical pigment network, irregular streaks, and blue-white structures. Minor criteria may include regression structures, irregular dots/globules, and vascular patterns.

Algorithm-based approaches provide structured frameworks for interpretation. The ABCD rule evaluates:

• Asymmetry in color and structure
• Border abruptness
• Color variation
• Dermoscopic structures

The 7-point checklist assigns weighted scores to specific features, with a total score ≥3 suggesting melanoma. Two-step dermoscopy involves first determining whether a lesion is melanocytic, then assessing its malignant potential. This method reduces false positives and improves specificity.

Recent advancements in dermatoscope with UV light technology have enhanced the visualization of these criteria, particularly in detecting subtle vascular patterns and sub-surface pigmentation that may indicate early malignant transformation.

III. Recognizing Subtle Dermoscopic Clues

Atypical pigment network represents one of the most important early signs of melanoma. Unlike the regular, honeycomb-like network of benign nevi, atypical networks show irregularly distributed thick lines with varying colors and abrupt termination at the periphery. This feature is particularly well-visualized using a dermoscope for dermatologist with cross-polarized light.

Irregular dots and globules appear as focal accumulations of melanin at different levels of the skin. In melanoma, these structures vary in size, shape, and distribution. Asymmetrical structures, when present in multiple axes, strongly suggest malignancy. Regression structures manifest as white scar-like areas (fibrosis) and blue-gray pepper-like granules (melanin incontinence).

The blue-white veil, a combination of blue pigmentation and white ground-glass haze, indicates compact orthokeratosis overlying melanin in the dermis. This feature has high specificity for melanoma, particularly when covering >10% of the lesion. Modern dermoscopes equipped with UV light can enhance detection of these subtle features, especially in early lesions.

IV. Dermoscopy in Different Skin Types

Diagnosing melanoma in darker skin presents unique challenges. While less common in Asian populations, melanomas in Hong Kong patients often present at more advanced stages, partly due to atypical clinical presentations. Specific dermoscopic features vary across ethnicities:

Acral melanomas, more common in Asian populations, show specific patterns like parallel ridge pattern on palms and soles. A dermatoscope with UV light can be particularly helpful in evaluating these lesions by enhancing contrast in heavily pigmented skin.

V. Case Studies: Dermoscopy in Action

Case 1: A 45-year-old Hong Kong businessman presented with a 4mm pigmented lesion on his back. Clinical examination showed slight asymmetry but no ulceration. Dermoscopy revealed:

• Atypical pigment network at periphery
• Irregular brown globules
• Focal blue-white veil

Excision confirmed in-situ melanoma. This case highlights how dermoscopy detected malignancy before classic clinical features appeared.

Case 2: A 60-year-old woman with dark skin (Fitzpatrick V) had a 6mm dark macule on her foot. Under dermoscope for dermatologist examination, the lesion showed:

• Parallel ridge pattern
• Irregular diffuse pigmentation
• Polymorphous vessels

Histopathology confirmed acral lentiginous melanoma. This demonstrates the importance of recognizing ethnic-specific patterns.

Common pitfalls include over-reliance on single features and failure to correlate dermoscopic findings with clinical context. Regular training and use of standardized algorithms can minimize these errors. The integration of dermatoscope with UV light technology into routine practice continues to improve early detection rates, particularly for subtle or early-stage melanomas that might otherwise be missed.

Posted by: softsea at 10:57 AM | No Comments | Add Comment
Post contains 770 words, total size 7 kb.