Dermoscopy for Non-Experts: Identifying Suspicious Skin Lesions

I. Introduction to Skin Cancer and the Importance of Early Detection

Skin cancer represents one of the most common malignancies worldwide, with Hong Kong experiencing a steady increase in cases over the past decade. According to the Hong Kong Cancer Registry, skin cancer ranks among the top ten most frequent cancers in the region, with approximately 1,200 new cases diagnosed annually. The three primary types of skin cancer include melanoma, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC). Melanoma, though less common than other forms, accounts for the majority of skin cancer-related deaths due to its aggressive nature and potential for metastasis. Squamous cell carcinoma typically develops in the epidermis and can spread to other body parts if left untreated, while basal cell carcinoma usually remains localized but can cause significant tissue damage.

Multiple risk factors contribute to skin cancer development, with ultraviolet (UV) radiation exposure being the most significant. In Hong Kong's subtropical climate, year-round sun exposure poses particular challenges for residents. Additional risk factors include fair skin, numerous moles, family history of skin cancer, immunosuppression, and previous radiation therapy. Prevention strategies emphasize sun protection measures such as using broad-spectrum sunscreen with SPF 30 or higher, wearing protective clothing, seeking shade during peak UV hours (10 am to 4 pm), and avoiding tanning beds entirely. Regular self-examination combined with professional skin checks forms the cornerstone of early detection, which dramatically improves treatment outcomes and survival rates.

The role of self-examination cannot be overstated in skin cancer detection. Individuals should perform thorough skin checks monthly, examining all areas of the body including hard-to-see locations like the scalp, between toes, and the back. Using mirrors or asking a partner for assistance can help visualize these difficult areas. The development of mobile dermatoscopy attachments has revolutionized self-examination, allowing individuals to document and monitor suspicious lesions over time. Early detection remains crucial – when identified at stage I, melanoma has a 5-year survival rate exceeding 95%, compared to approximately 25% for stage IV disease. This dramatic difference underscores why understanding basic dermoscopic principles and recognizing warning signs can be life-saving knowledge for non-experts.

II. Dermoscopy Basics for Non-Experts

A dermatoscope represents a specialized handheld device that combines magnification with polarized light to visualize subsurface skin structures normally invisible to the naked eye. Understanding basic dermatoscope uses empowers non-experts to better monitor their skin health between professional examinations. Modern dermatoscopes typically feature 10x magnification and employ either polarized or non-polarized light technology. Polarized light reduces skin surface reflection, allowing visualization of structures in the dermo-epidermal junction and papillary dermis, while non-polarized light (often with immersion fluid) reveals different morphological features. The fundamental principle behind dermoscopy involves making the stratum corneum translucent, thereby enabling examination of patterns, colors, and structures beneath the skin surface.

When beginning dermoscopic examination, non-experts should focus on recognizing basic dermoscopic features including colors, patterns, and specific structures. Common colors observed through dermatoscopy include:

• Light brown to dark brown: typically indicates melanin in different skin layers
• Black: often represents concentrated melanin or necrosis
• Blue-gray: suggests melanin in the deep dermis
• Red: indicates vascular structures or inflammation
• White: may represent regression or fibrosis
• Yellow: often corresponds to keratin or serum

Pattern recognition forms another crucial aspect of dermoscopy for non-experts. Common patterns include reticular (network-like), globular (round structures), homogeneous (structureless), and starburst (radial projections). Specific structures to recognize include dots (small round structures), globules (larger round or oval structures), streaks (linear radial extensions), and vascular patterns (including dotted vessels, linear irregular vessels, and hairpin vessels). Understanding these basic elements provides a foundation for recognizing potentially dangerous lesions that warrant professional evaluation.

Familiarity with common dermoscopic terminology helps non-experts better communicate concerns to healthcare providers and understand educational resources. Essential terms include:

• Pigment network: grid-like pattern formed by melanocytes at the dermo-epidermal junction
• Regression structures: white scar-like areas and blue-gray peppering indicating tumor involution
• Milia-like cysts: small white-yellowish round structures representing keratin inclusions
• Comedo-like openings: dark pores filled with keratin
• Arborizing vessels: tree-like branching vessels typically associated with basal cell carcinoma

While non-experts shouldn't attempt definitive diagnosis, recognizing these basic elements helps identify lesions requiring professional assessment. Modern technology has expanded dermatoscope uses through smartphone attachments and AI-assisted analysis applications, though these should complement rather than replace professional dermatological consultation.

III. Recognizing Dermoscopic Clues for Melanoma

Melanoma recognition through dermoscopy relies heavily on pattern analysis and the ABCD rule specifically adapted for dermoscopic evaluation. The dermoscopic ABCD rule stands for Asymmetry, Border, Colors, and Different structural components. Asymmetry in dermoscopy refers to both contour asymmetry and color/structure asymmetry when the lesion is divided along multiple axes. Border assessment focuses on abrupt termination of pigment pattern at the lesion's periphery, often appearing as sharp cut-off points rather than gradual fading. Color evaluation involves identifying multiple colors (typically five or six) including shades of brown, black, red, white, and blue-gray. Different structural components refer to the presence of diverse dermoscopic structures within a single lesion.

When examining dermoscopy images of melanoma, non-experts should specifically look for:

• Asymmetrical pattern and structure across two perpendicular axes
• Irregular borders with abrupt edge termination
• Multiple colors (typically three or more) unevenly distributed
• Diameter larger than 6mm (though early melanomas may be smaller)
• Presence of atypical vascular patterns including dotted, linear irregular, or polymorphous vessels
• Radial streaming or pseudopods at the lesion periphery
• Blue-white veil overlying parts of the lesion
• Negative network (white network-like pattern)
• Shiny white lines (also called chrysalis or crystalline structures)

Analysis of dermoscopy images of melanoma reveals characteristic patterns that distinguish them from benign lesions. For instance, superficial spreading melanoma often demonstrates an atypical pigment network, irregular dots and globules, and multiple colors. Nodular melanoma frequently shows blue-white veil, polymorphous vessels, and structureless areas with occasional ulceration. Lentigo maligna melanoma typically displays asymmetrical pigmented follicular openings, rhomboidal structures, and annular-granular patterns. Acral melanomas on palms and soles often reveal parallel ridge patterns, where pigment follows the skin ridges rather than the furrows (which is typical of benign acral nevi).

Non-experts should understand that no single feature definitively diagnoses melanoma; rather, it's the constellation of multiple concerning findings that warrants professional evaluation. The CASH algorithm (Color, Architecture, Symmetry, and Homogeneity) provides another systematic approach for non-experts to evaluate lesions. Additionally, the "Ugly Duckling" sign – where one lesion looks distinctly different from others on the same person – remains a valuable recognition strategy even with dermoscopy. When multiple concerning features are present, particularly when documented changes occur over time, prompt dermatological consultation is essential.

IV. Recognizing Dermoscopic Clues for Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) presents distinct dermoscopic features that differ significantly from melanoma. Understanding dermoscopy of squamous cell carcinoma enables earlier detection and intervention. SCC arises from keratinocytes in the epidermis and typically develops in sun-exposed areas, making regular dermoscopic monitoring of these areas particularly important. The dermoscopic presentation of SCC varies depending on its clinical variant and stage, but several characteristic features help distinguish it from benign lesions and other skin malignancies.

The most prominent features in dermoscopy of squamous cell carcinoma include keratinization, ulceration, and specific vascular patterns. Keratinization manifests as white to yellow surface scale, keratin masses, or central keratin plugs. These keratin deposits often appear as amorphous yellow-white areas that may obscure underlying structures. Ulceration presents as well-defined, red depressions with or without blood crusts, typically persisting for weeks without healing. The vascular patterns in SCC are particularly distinctive and include:

• Glomerular vessels: coiled or twisted vessels resembling renal glomeruli
• Hairpin vessels: U-shaped vessels often surrounded by white halos
• Linear-irregular vessels: meandering vessels with varying caliber and distribution
• Dotted vessels: small red points regularly or irregularly distributed

These vascular patterns often cluster within the lesion and demonstrate irregular distribution and morphology. In Hong Kong, where actinic keratoses (precursors to SCC) are common due to high sun exposure, recognizing early dermoscopic signs becomes particularly important. Actinic keratoses typically display a strawberry pattern characterized by red pseudonetwork surrounding hair follicles with white-yellow scales on a reddish background. As these lesions progress to SCC in situ, they develop more prominent scale, stronger red pseudonetwork, and targetoid hair follicles. Invasive SCC typically shows more pronounced vascular patterns, thicker scale crust, and ulceration.

Bowen's disease (SCC in situ) presents distinctive dermoscopic features including small scale, glomerular vessels typically arranged in clusters or groups, and brownish dots or globules sometimes arranged in linear patterns. Keratoacanthoma-type SCC often demonstrates a central keratin crater surrounded by hairpin vessels with white halos. Pigmented SCC, though less common, shows additional features including gray-blue dots, brown dots and globules, and structureless brown areas. Non-experts should pay particular attention to any lesion demonstrating combinations of scale/crust, ulceration, and atypical vascular patterns, especially in sun-exposed areas, as these warrant prompt professional evaluation.

V. When to Seek Professional Help

Recognizing when to seek professional dermatological evaluation represents the most crucial application of dermoscopy knowledge for non-experts. Certain warning signs and symptoms should trigger immediate consultation regardless of dermoscopic findings. These include any lesion that bleeds spontaneously without trauma, itches persistently, causes pain or tenderness, changes rapidly in size, shape, or color, or fails to heal within three weeks. The mnemonic "EFG" (Elevated, Firm, Growing) helps identify nodular melanomas that might not display classic ABCD features. Additionally, any new lesion appearing after age 40, particularly if it looks different from other moles, warrants professional assessment.

Regular dermatological check-ups form an essential component of skin cancer prevention and early detection. The recommended frequency depends on individual risk factors. High-risk individuals include those with personal or family history of skin cancer, numerous moles (>50), atypical moles, fair skin that burns easily, significant childhood sun exposure, immunosuppression, or previous radiation therapy. For high-risk individuals, annual full-body skin examinations by a qualified dermatologist are recommended. Moderate-risk individuals should undergo professional skin checks every 2-3 years, while low-risk individuals may benefit from baseline examination and education on self-examination techniques. In Hong Kong, the Department of Health recommends annual skin checks for all adults over 50 due to cumulative sun exposure effects.

Finding a qualified dermatologist ensures proper evaluation of suspicious lesions. When selecting a dermatologist, verify their credentials including medical license, board certification in dermatology, and specific training in dermoscopy. Many dermatologists in Hong Kong list their specialized training and areas of expertise on the Hong Kong College of Dermatologists website. During consultation, expect the dermatologist to take a thorough history including family history of skin cancer, sun exposure patterns, and previous skin lesions. The examination should include full-body skin inspection using dermoscopy for suspicious lesions. If a lesion raises concern, the dermatologist should explain the rationale for biopsy or monitoring and discuss the procedure, potential outcomes, and follow-up plan. Establishing an ongoing relationship with a dermatologist facilitates continuity of care and enables more accurate monitoring of lesion changes over time.