The Dermoscopy Examination: A Step-by-Step Procedure for Skin Lesion Assessment

Introduction to Dermoscopy Examination

dermoscopy examination represents a revolutionary advancement in dermatological diagnostics, serving as a non-invasive imaging technique that enables clinicians to visualize subsurface skin structures not visible to the naked eye. The primary purpose of this sophisticated tool is to enhance diagnostic accuracy for various skin conditions, particularly in the early detection of malignant lesions such as melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma. By magnifying the skin's surface up to 100 times and eliminating surface reflection, dermoscopy provides unparalleled visualization of morphological features in the epidermis, dermo-epidermal junction, and papillary dermis.

Indications for dermoscopy have expanded significantly over the past decade. According to the Hong Kong Dermatological Society, approximately 85% of dermatologists in Hong Kong now routinely use dermoscopy for evaluating pigmented skin lesions, with growing applications in non-pigmented conditions. Key indications include: differentiation between benign and malignant melanocytic lesions; diagnosis of basal cell carcinoma through specific dermoscopic patterns; evaluation of vascular structures in inflammatory and neoplastic conditions; assessment of nail apparatus disorders; and monitoring of lesion evolution over time. The technique has proven particularly valuable in Hong Kong's diverse population, where skin cancer incidence has increased by approximately 30% over the past 15 years according to the Hong Kong Cancer Registry.

While dermoscopy examination offers numerous benefits, certain contraindications and precautions warrant consideration. Absolute contraindications are minimal, but relative precautions include: examination of ulcerated lesions with active bleeding; evaluation of highly inflamed or infected skin where contact might spread infection; and assessment of patients with known allergies to immersion fluids. Additionally, practitioners must recognize that dermoscopy requires substantial training and experience to interpret findings accurately. The Hong Kong College of Dermatologists emphasizes that inadequate training remains the most significant barrier to effective implementation, with studies showing diagnostic accuracy improves from approximately 60% with naked-eye examination to over 90% with proper dermoscopic training.

Preparing for the Dermoscopy Examination

Proper patient preparation forms the foundation of a successful dermoscopy examination. The process begins with obtaining informed consent, particularly when capturing and storing digital images. Patients should receive clear explanations about the procedure's purpose, benefits, and limitations. Practical preparation includes ensuring the skin area to be examined is clean and free from makeup, lotions, or ointments that might interfere with visualization. For hairy areas, gentle clipping may be necessary to improve visualization, though shaving should be avoided as it might cause micro-abrasions that alter dermoscopic features. Patient positioning should provide maximum comfort and stability, with appropriate support for elderly or mobility-impaired individuals commonly seen in Hong Kong's aging population.

Equipment selection critically influences dermoscopy examination quality. The fundamental choice between immersion and polarization dermoscopes depends on clinical needs and preferences:

• Immersion dermoscopy requires direct contact with the skin using a fluid interface (such as alcohol gel, ultrasound gel, or water) to eliminate surface reflection. This method provides superior visualization of deeper structures but requires cleaning between patients.
• Polarized dermoscopy uses cross-polarized filters to cancel out surface reflection without direct skin contact. This technique better highlights vascular patterns, colors, and melanin but may not visualize some deeper structures as clearly.

Many modern devices offer hybrid capabilities, allowing switching between modes. For immersion fluid selection, isopropyl alcohol (70-90%) remains the standard due to its optimal refractive index and disinfectant properties. Alternative options include ultrasound gel, which provides excellent optical quality but requires thorough cleaning, and mineral oil, preferred for scalp examinations. Cleaning supplies must include hospital-grade disinfectants compatible with the dermoscope's materials, with Hong Kong's strict infection control protocols recommending at least 70% alcohol solutions or approved surface disinfectants.

The examination room setup significantly impacts workflow efficiency and patient experience. Optimal conditions include:

Hong Kong's compact clinical spaces often require creative solutions, but maintaining these fundamental elements ensures consistent examination quality. Additional considerations include having a reliable power source, backup equipment, and efficient image management systems compatible with Hong Kong's electronic health record requirements.

Step-by-Step Dermoscopy Procedure

The dermoscopy procedure begins with a thorough initial assessment of the skin lesion using naked-eye examination. This crucial first step establishes clinical context and helps identify which lesions require detailed dermoscopic evaluation. The clinician should note the lesion's anatomical location, size, shape, color, and relationship to surrounding skin. Particular attention should be paid to the ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution) while recognizing that these guidelines have limitations, especially in Asian populations where acral and subungual melanomas are more prevalent. In Hong Kong, where healthcare providers encounter diverse skin types, additional consideration should be given to variations in dermoscopic features across different ethnicities.

Application of immersion fluid represents a critical technical step in contact dermoscopy. The fluid must be applied generously enough to create a continuous layer between the dermoscope and skin, eliminating air bubbles that can obscure visualization. The recommended technique involves placing a small amount of fluid directly on the lesion or on the dermoscope's plate, then gently bringing the instrument into contact with the skin. For larger lesions, the fluid should be applied to the entire area to be examined. When using alcohol-based solutions, patients should be warned about possible cooling sensation, while those with sensitive skin might benefit from hypoallergenic alternatives. Proper fluid application significantly enhances the visualization of structures crucial for diagnosis, particularly in dermoscopy of bcc where specific features like ulceration, blue-gray ovoid nests, and arborizing vessels might be subtle.

Effective dermoscope operation requires mastery of several technical elements. Focus adjustment should begin with the instrument slightly away from the skin, gradually bringing it closer until optimal clarity is achieved. Light intensity should be adjusted to provide adequate illumination without causing glare or washing out colors, with lower settings often preferable for vascular structures and higher settings for pigmented lesions. Systematic scanning follows established patterns, typically beginning at the lesion's center and moving radially, or using a zig-zag pattern to ensure complete coverage. Each lesion should be examined from multiple angles, with particular attention to border areas where malignant changes often originate. The entire process should be methodical and reproducible, with experienced practitioners in Hong Kong typically spending 30-60 seconds per lesion for comprehensive evaluation.

Identification of dermoscopic structures and patterns forms the diagnostic core of the examination. Key elements to recognize include:

• Pigment network: Honeycomb-like pattern representing melanin in rete ridges
• Dots and globules: Roundish structures varying in size, color, and distribution
• Streaks: Radial projections at lesion periphery
• Blue-white structures:
• Vascular structures: Morphology and distribution of blood vessels

Pattern recognition requires understanding how these elements combine to form diagnostic patterns. For example, in dermoscopy of BCC, the absence of pigment network combined with the presence of leaf-like areas, large blue-gray ovoid nests, spoke-wheel areas, and arborizing vessels creates a distinctive pattern with diagnostic sensitivity exceeding 90%. Documentation of negative findings (absence of expected features) can be equally important, particularly when ruling out melanoma in atypical lesions.

Dermoscopic Interpretation

Accurate dermoscopic interpretation requires systematic evaluation of key features that differentiate benign from malignant lesions. The most critical elements include pigment network characteristics (regular vs irregular), distribution of colors (presence of more than three colors raises concern), and specific morphological structures. For melanocytic lesions, the CASH algorithm (Color, Architecture, Symmetry, Homogeneity) provides a structured approach, while for non-melanocytic lesions, pattern analysis focuses on features specific to different tumor types. In dermoscopy of BCC, the presence of any of these major criteria—large blue-gray ovoid nests, multiple blue-gray globules, leaf-like areas, arborizing vessels, ulceration—strongly supports the diagnosis, with studies from Hong Kong showing 97% sensitivity when at least one feature is present.

Diagnostic algorithms and checklists provide valuable frameworks for standardized interpretation, particularly for less experienced practitioners. The most widely validated include:

While these tools provide valuable structure, they cannot replace clinical judgment. The Hong Kong Dermatological Society recommends using algorithms as guides rather than absolute determinants, with particular attention to lesion evolution and patient risk factors.

Clinical correlation remains the cornerstone of accurate dermoscopic interpretation. The most sophisticated dermoscopic analysis must be integrated with clinical information including patient history, skin type, anatomical location, and lesion history. This integration is particularly important in populations with diverse skin phenotypes, such as Hong Kong's mixed Chinese and expatriate population. Features that might suggest malignancy in fair skin may have different significance in darker skin types. Additionally, knowledge of regional variations in skin cancer presentation is essential—for instance, in Hong Kong, where basal cell carcinoma represents approximately 65% of all skin cancers but melanoma accounts for only 15%, though with higher mortality. The clinician must always ask: Do the dermoscopic findings align with the clinical presentation? If not, what might explain the discrepancy?

Documenting the Dermoscopy Examination

High-quality image documentation serves multiple crucial functions in dermoscopy examination: creating a permanent record for comparison over time, enabling second opinions, supporting teledermatology consultations, and providing medical-legal protection. Optimal technique requires consistent positioning, proper focus, and adequate lighting. The basic documentation protocol should include:

• Clinical overview image showing the lesion in anatomical context
• Standardized dermoscopic image with scale reference
• Multiple views for large or complex lesions
• Consistent imaging parameters (distance, angle, lighting) for serial comparisons

Modern dermoscopy systems often incorporate digital cameras with resolutions exceeding 10 megapixels, sufficient for capturing fine details. For practices in Hong Kong, where space constraints often limit equipment options, handheld devices with built-in cameras offer practical solutions. Regardless of equipment level, consistency in technique matters more than technological sophistication. Including a color calibration target in one image per session ensures accurate color representation across different viewing platforms.

Comprehensive recording of dermoscopic findings transforms images into clinically actionable information. The documentation should systematically capture:

This structured approach ensures nothing is overlooked and facilitates communication with other healthcare providers. In Hong Kong's multidisciplinary cancer care environment, clear documentation becomes especially important when referring patients for specialist management.

Creating a comprehensive patient report represents the final step in documentation. The ideal report integrates clinical information, dermoscopic findings, and management recommendations in a clear, standardized format. Essential components include patient demographics, relevant medical history, clinical images, dermoscopic images with annotations, structured description of findings, diagnostic interpretation, and specific management recommendations. For electronic health record systems commonly used in Hong Kong, template-based reporting improves efficiency while maintaining completeness. The report should be written in language understandable to both healthcare professionals and patients, with particular attention to clarity when recommending surveillance versus intervention. In medicolegally conscious environments like Hong Kong, including a statement about limitations (e.g., "dermoscopy cannot exclude malignancy with 100% accuracy") provides important context for management decisions.

Best Practices and Tips for Successful Dermoscopy

Avoiding common pitfalls significantly enhances dermoscopy examination value. The most frequent errors include inadequate lesion preparation (residual makeup, oils, or scales), insufficient immersion fluid causing air artifacts, excessive pressure that blanches vascular structures, and failure to examine the entire lesion including periphery. Cognitive errors represent equal challenges, particularly satisfaction of search (stopping examination once one feature is found), anchoring bias (clinging to initial impression despite contradictory evidence), and overreliance on algorithms without clinical correlation. Technical pitfalls specific to dermoscopy of BCC include misinterpreting keratin as ulceration or overlooking subtle blue-gray globules in heavily pigmented variants. Regular quality assurance reviews, preferably with blinded case discussions, help identify and correct these tendencies.

Enhancing diagnostic skills requires deliberate practice and continuous education. Effective strategies include:

• Establishing a personal library of proven cases with histopathological correlation
• Participating in regular case discussions with colleagues
• Attending hands-on workshops with expert feedback
• Completing structured online education programs
• Reviewing personal accuracy through biopsy track-backs

Hong Kong offers numerous educational opportunities through the Hong Kong College of Dermatologists and university teaching hospitals, with particular emphasis on pattern recognition in Asian skin. Studies consistently show that diagnostic accuracy plateaus after reviewing approximately 500-1,000 lesions under expert supervision, highlighting the importance of volume and feedback in skill development. Maintaining a log of examined lesions with outcomes provides valuable data for self-assessment and identifies areas needing improvement.

The future of dermoscopy technology promises exciting advancements that will further enhance diagnostic capabilities. Current developments include artificial intelligence algorithms that can analyze dermoscopic images with accuracy rivaling expert dermatologists, with several systems already achieving 95%+ sensitivity for melanoma detection in controlled studies. Other emerging technologies include 3D dermoscopy for better assessment of lesion topography, multispectral imaging that captures information beyond visible light, and confocal microscopy integration providing cellular-level resolution. For Hong Kong's healthcare system, where efficiency demands are high, teledermoscopy platforms enable remote specialist consultations and automated lesion tracking over time. However, these technological advances must complement rather than replace clinical expertise, with the human element remaining essential for integrating dermoscopic findings with patient context and preferences. The most successful practitioners will be those who leverage technology while maintaining fundamental diagnostic skills and clinical judgment.

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