Dermoscopy in China: Current Status and Future Prospective

Introduction

Dermoscopy is a non-invasive diagnostic tool that has significantly enhanced the accuracy of diagnosing various skin disorders. By capturing detailed characteristics of skin lesions and eliminating the influence of surface light, dermoscopy allows clinicians to observe subsurface structures such as the epidermis, dermal papilla, and pigmentation in vivo. This technique has become a cornerstone in the early diagnosis, screening, and computer-aided detection of skin diseases. Over the past decade, dermoscopy has gained widespread acceptance in China, where it has been instrumental in improving diagnostic sensitivity and specificity for a range of skin conditions, including skin cancer and inflammatory dermatoses. Beyond diagnosis, dermoscopy is also used to define tumor margins, evaluate treatment efficacy, and classify diseases.

Diagnostic Value of Dermoscopy

Dermoscopy has proven to be a valuable tool in increasing the sensitivity of skin cancer detection while reducing the number of unnecessary biopsies for benign lesions. In China, more than half of the studies on dermoscopy focus on describing the dermoscopic characteristics of skin diseases, which assist dermatologists in making accurate diagnoses. The sensitivity and specificity of dermoscopy for various skin conditions in China are summarized in Table 1.

Condylomata Acuminata (CA)

Condylomata acuminata (CA), caused by the human papillomavirus, typically appears in genital areas. Dermoscopic patterns of CA include non-specific, fingerlike, mosaic, and knoblike patterns. Characteristic vascular features such as dotted, annular, dendritic, and hairpin vessels are also observed. Compared to naked-eye examination, which has a sensitivity of 87.7%, dermoscopy improves the sensitivity of diagnosing CA to 97.4%. This non-invasive technique is particularly useful for identifying lesions that are invisible to the naked eye.

Basal Cell Carcinoma (BCC)

Basal cell carcinoma (BCC) is one of the most common skin cancers in China. Dermoscopic criteria for BCC are influenced by factors such as histopathologic subtype, location, gender, age, and pigmentation traits. Key dermoscopic features include arborizing vessels, superficial fine telangiectasias, blue-gray ovoid nests, and shiny white/red structureless areas. In China, the sensitivity of dermoscopy for diagnosing tiny pigmented BCCs is as high as 97.2%, with specificity ranging from 70.0% to 87.5%. Despite variations in specificity due to differences in skin pigmentation and dermatologists’ experience, dermoscopy shows a high correlation with histopathology in diagnosing BCC.

Actinic Keratosis (AK) and Squamous Cell Carcinoma (SCC)

Actinic keratosis (AK) is a pre-cancerous lesion associated with long-term ultraviolet exposure, with a risk of progressing to squamous cell carcinoma (SCC). Dermoscopic features of non-pigmented AK include keratin/scales, a “strawberry” pattern, and a red pseudo-network. For pigmented AK, a brownish to gray pseudo-network and dark-brown dots around follicular ostia are observed. The sensitivity and specificity of dermoscopy for diagnosing AK are 97.2% and 83.3%, respectively. Dermoscopy also aids in the early diagnosis of SCC developing from AK, helping to avoid unnecessary biopsies.

Melanoma, Nevus, and Seborrheic Keratosis (SK)

Melanoma, nevus, and seborrheic keratosis (SK) are often clinically confusing due to their similar appearances. A two-step algorithm for diagnosing SK, which includes an exclusion algorithm followed by a diagnostic algorithm, has been proposed. In China, the sensitivity of this algorithm was improved from 79.1% to 95.7% by adding criteria such as lack of blue-gray or blue-white color and sharp demarcation. For nevus, a sensitivity of 72.2% and specificity of 87.5% were reported, though these figures may be influenced by stringent diagnostic criteria and small sample sizes. While there is limited data on melanoma in China, international studies suggest that dermoscopy increases the sensitivity of melanoma diagnosis from around 60% to 90%.

Treatment Efficacy

Dermoscopy is not only a diagnostic tool but also a valuable instrument for evaluating treatment efficacy. By observing micro-structures invisible to the naked eye, dermoscopy can accurately record and judge changes in lesion conditions. In China, dermoscopy has been used to assess the efficacy of treatments for various skin conditions, including port wine stains, infantile hemangiomas, and vitiligo.

Port Wine Stains and Infantile Hemangiomas

For port wine stains, signs of vascular rupture and punctate or globular hemorrhagic shadows observed through dermoscopy indicate better treatment efficacy and appropriate dosing. Similarly, the regression of vasculature in infantile hemangiomas is a key indicator of treatment success.

Vitiligo and Melanosis

In patients with vitiligo, the formation of early pigmentation islands is a critical dermoscopic feature used to judge treatment efficacy. For melanosis, the number of gray-brown dots or small balls observed under dermoscopy is used to assess treatment outcomes. Dermoscopy enables the detection of subtle changes that are not visible to the naked eye, improving patient compliance and treatment efficacy.

Neoplastic Diseases

Dermoscopy is also used to determine treatment endpoints and follow-up in neoplastic diseases. Clinicians use dermoscopy to monitor residual lesions and assess the risk of recurrence. Additionally, dermoscopy has been employed to evaluate the therapeutic effects of facial rejuvenation and androgenetic alopecia (AGA).

Psoriasis and Acne Vulgaris

In psoriasis, dermoscopy has been used to observe vascular changes, which correlate with disease severity. As treatment progresses, the diameter of glomerular vessels decreases, indicating a positive response. Similarly, in acne vulgaris, dermoscopy has been used to monitor changes in skin texture, pore size, and oily scales following laser treatment.

Disease Classification

Dermoscopy has shown promise in classifying and staging various skin diseases, providing more accurate assessments of disease severity. In China, dermoscopy has been used to classify alopecia areata, scars, and androgenetic alopecia (AGA).

Androgenetic Alopecia (AGA)

AGA, a progressive hair loss disease, is classified into 12 grades for men and three grades for women based on the Hamilton-Norwood classification. Dermoscopic parameters such as hair coverage, hair density, and the ratio of vellus to terminal hairs are used to assess disease severity. Combining dermoscopic parameters with clinical images has resulted in good consistency and reproducibility in grading AGA.

Alopecia Areata

Alopecia areata is classified into active, quiescent, and recovery phases. Dermoscopic signs such as yellow spots, black dots, broken hair, and short vellus hairs are used to classify the disease. Black dots and broken hair are characteristic of the active phase, while the appearance of short vellus hairs indicates recovery.

Chloasma and Hypertrophic Scars

In chloasma, vascular morphology scores obtained through dermoscopy are used to assess treatment efficacy but not disease stage. For hypertrophic scars, dermoscopy is used to evaluate vascularity and pigmentation, providing a potential tool for assessing scar maturation.

Determination of Tumor Margins

Dermoscopy has been increasingly used in surgical settings to determine tumor margins, particularly for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Studies have shown that dermoscopic detection of surgical excision margins is superior to naked-eye observation, reducing the risk of recurrence and the need for secondary surgery. In addition, dermoscopy has been used to guide suturing in small surgical spaces, demonstrating its versatility in surgical applications.

Training and Education

The accuracy of dermoscopic diagnosis depends heavily on the experience and training of the examiner. In China, training courses, both face-to-face and online, have been offered to improve dermatologists’ diagnostic abilities. The Chinese Skin Image Database (CSID), launched in 2017, has played a pivotal role in promoting dermoscopy education and research. The CSID-Skin Imaging College, an online platform, has provided dermatologists with access to micro-courses on dermoscopy, significantly enhancing their diagnostic skills.

Computer-Aided Diagnosis (CAD)

Computer-aided diagnosis (CAD) systems based on dermoscopic images have the potential to improve the efficiency and accuracy of skin disease diagnosis. Traditional CAD systems involve artifact and noise reduction, lesion segmentation, feature extraction, and classification. In China, deep learning algorithms have been widely used for dermoscopic image classification, achieving results comparable to those of experienced dermatologists. The development of CAD systems based on the Chinese population has been facilitated by the CSID, which has collected over 200,000 multi-dimensional skin imaging data sets.

Future Directions

Despite the significant progress in dermoscopy in China, several challenges remain. Strengthening cooperation and conducting large-scale, multi-center clinical research are essential for identifying more accurate dermoscopic features. Improving dermatologists’ ability to use dermoscopy through systematic training is also crucial. Additionally, the establishment of a standardized dermoscopic image database and the development of teledermoscopy and artificial intelligence-based diagnostic tools are key future trends.

Conclusion

Dermoscopy has become an indispensable tool in dermatology in China, offering significant improvements in the diagnosis, treatment, and classification of skin diseases. The development of the CSID and the widespread adoption of training programs have further enhanced the use of dermoscopy in clinical practice. However, continued efforts are needed to address challenges such as the need for more extensive research, improved training, and the development of advanced diagnostic tools. As dermoscopy continues to evolve, it holds great promise for advancing dermatological care in China.

doi.org/10.1097/CM9.0000000000000396

Was this helpful?

YesNo

0 / 0