Dermoscopy Aids in the Diagnosis of Discoid Lupus Erythematosus

Herein, we present a protocol to demonstrate the utility of dermoscopy in rheumatic diseases. In addition, we described the dermoscopic manifestations of discoid lupus erythematosus skin lesions.

Dermoscopy is an important non-invasive form of examination that plays a critical role in the diagnosis of rheumatic diseases accompanied by skin lesions. This technique is performed in real-time and can thus assist in determining the skin biopsy site. Skin lesions are common and important manifestations of most rheumatic diseases, including lupus erythematosus. In some rheumatic diseases, such as rheumatoid arthritis, the incidence of skin rashes may not be as high; however, those lesions that do develop can be diverse and deceptive, thereby complicating diagnosis. Dermoscopy and the observation of microscopic characteristics can assist in diagnosing primary diseases in their early stages. Herein, we present a protocol that provides a detailed overview of the standardized operation process of dermoscopy. Further, using discoid lupus erythematosus as an example, we demonstrate the important role of dermoscopy in the diagnosis of many different rheumatic diseases. Finally, we discuss the diverse dermoscopic manifestations of different rheumatic diseases and their associated skin lesions.

Dermoscopy is an emerging non-invasive diagnostic technique that has been widely applied in various dermatological diseases, playing an important role in the early stages of diagnosis. It is becoming increasingly used in the diagnosis of inflammatory and rheumatic diseases. This technique has the advantages of being non-invasive and performed in real-time, thus assisting in determining the site of skin biopsy. The basic principle of dermoscopy involves the use of a liquid interface or polarized light technology to reduce the backscattered light caused by the skin's stratum corneum; this allows magnification of lesions by a factor of tens to hundreds, facilitating further observation of the structure under the stratum corneum and even the superficial dermis. This visualization not only aids in the diagnosis and differential diagnosis of the disease but also helps in guiding the treatment and judging treatment efficacy¹. This technique circumvents the pain, trauma, and scarring caused by invasive examinations and reduces pain in patients. Currently, two types of dermoscopy are applied: polarization (Dermoscopy Polari-light, DP) and infiltration (Dermoscopy Soakage, DS)². Classical dermoscopy is performed by infiltrating the skin with fluid to increase light transmission and reduce the amount of reflected light. Polarized light dermoscopy, which has been developed in recent years, further allows the observation of subcutaneous structures without the use of an infiltrating solution by filtering out diffusely reflected light from the skin surface using a polarizing filter.

Discoid lupus erythematosus (DLE) is the most common form of cutaneous lupus which generally affects sun-exposed areas such as the face, scalp, and upper trunk. The skin lesions in patients with DLE show significant variation. Differentiating DLE lesions on the scalp and other areas from inflammatory, neoplastic, or infectious diseases may be challenging in some cases. Currently, DLE can be diagnosed using methods such as clinicians' observation of skin lesions, skin biopsy, and non-invasive examinations like dermoscopy. Skin biopsy has long been an important method for DLE diagnosis, as pathological analysis of tissue samples provides reliable evidence. However, it has limitations. It is an invasive procedure, causing pain to patients and carrying risks such as infection, bleeding, and scarring, which may lead some patients to refuse it. Moreover, the tissue samples are limited, with a risk of sampling error. If the sample is not from a typical lesion area, misdiagnosis or missed diagnosis may occur. The pathological examination is complex and time-consuming, usually taking days to weeks, potentially delaying treatment. It is also difficult to perform a biopsy of every suspected DLE skin lesion. Additionally, visual inspection cannot reveal deep-layer skin structures and lesion details, making it difficult to diagnose early hidden lesions or cases with unobvious appearance changes during disease progression.

Dermoscopy can aid with early differential diagnosis and selection of suitable sites for skin biopsy. It can also provide more detailed information that is difficult to observe with the naked eye and has obvious advantages in improving diagnostic accuracy, sensitivity, and specificity³, assisting in disease staging and assessment, and differential diagnosis. Therefore, it is a very effective adjuvant diagnostic tool. This examination can be performed on infants, pregnant women, and the elderly without any absolute contraindications. From a pathological perspective, DLE lesions are mainly characterized by epidermal hyperkeratosis, formation of follicular plugs, liquefaction degeneration of basal cells, and lymphocytic infiltration around the blood vessels and appendages in the superficial dermis⁴. The features observed under dermoscopy are the direct reflection of these pathological changes on the skin surface. For example, follicular plugs present as black or brown punctate or conical structures under dermoscopy, which is consistent with the pathological changes of hyperkeratosis of follicular epithelial cells and accumulation of keratinous substances at the follicular orifice. Vascular dilation and abnormal morphology are related to the vascular changes caused by inflammation around the blood vessels in the superficial dermis³.

The protocol was approved by the Ethics Committee of Shanghai Dermatology Hospital. The study obtained consent from the patient/participant to use the images/data in the publication.

1. Preparation

1. Patient screening
   1. Begin by reviewing the patient's medical history and conducting a physical examination.
   2. Identify patients with suspected DLE, particularly those with erythema on the face and other exposed areas, often accompanied by adherent scales. While these areas are typically affected, consider other locations as well.
2. Contraindications
   1. When performing this procedure, despite the absence of absolute contraindications, categorically exclude patients incapable of cooperating with the examination or refusing to undergo the procedure.
3. Preparing the examination environment
   1. Ensure the examination room is well-lit. Open the blinds or curtains to allow natural light to fill the room.
   2. If natural light is insufficient, use additional artificial lighting that provides clear, even illumination.
   3. Set the room temperature (RT) to a comfortable level, typically around 20-25°C. Ensure the room is clean, organized, and free from distractions or obstructions.

2. Dermoscopy examination procedure

1. Patient positioning
   1. Guide the patient into the examination room and have the patient sit on the examination chair or lie on the examination bed, if necessary. Position the examination chair against a black curtain or similar background to expose the skin lesions fully.
   2. Cleanse the skin with a mild, non-irritating cleanser(75% alcohol swabs) to remove oil, dirt, or cosmetics. For areas such as the scalp that require shaving, carefully shave the area using a clean, sharp razor, avoiding abrasions or cuts. Ensure that the skin is completely dry before proceeding to the next step.
2. Examination process
   1. Double-click the software icon in the computer system to start the dermoscopy. Check the dermoscopy device's magnification levels (usually 20× to 40×) and the quality of polarized light and ensure the overall functionality of the device.
   2. Use the high-definition camera mode of the dermascope to capture a general photograph of the skin lesions.
   3. Disinfect the lens of the dermatoscope with a cotton ball soaked in 75% alcohol and gently dry it.
   4. Gently place the dermoscopy on the skin's surface to examine. Slowly adjust the focus knob until the skin lesion is clearly visible.
   5. Switch the polarized light mode to enhance the visibility of the skin structures.
   6. Observe the shape of the lesion, noting any irregularities or asymmetries.
      1. Examine the color for any variations in pigmentation. Inspect the vascular structure, paying attention to the pattern and density of blood vessels; thick arborizing vessels are always detected in DLE skin lesions.
      2. Adjust the magnification by pressing the + and - buttons on the lens to view the lesion from different angles, ensuring that all relevant details are captured.
   7. Hold the dermoscopy steadily with the hand and gently change the angle between the dermoscopy and the skin surface. Make sure to move slowly and slightly to avoid large changes that could affect the observation.
   8. Continuously observe the image in the dermoscopy and stop adjusting when the image is clearest.

3. Recording and analysis

1. Feature recording
   1. Document the dermoscopic features of the skin lesions and make a detailed descriptive record of the lesions. Skin lesions such as black or brown punctate structures at the hair follicle orifices, red arborizing vessels, and punctate or circular vessels around the hair follicles are often observed in cases of DLE.
2. Final diagnosis
   1. After completing the dermoscopic examination and gathering all necessary information, review the patient's clinical manifestations, medical history, and other relevant examination results. Based on this comprehensive assessment, make a final diagnosis.
3. Recommendations and follow-up
   1. If the diagnosis is clear, provide the patient with appropriate recommendations, which may include lifestyle modifications, topical treatments, or referrals to other specialists.
   2. If further examination or treatment is required, explain the need for additional steps in detail. Develop a follow-up plan outlining the next steps, the expected timeline for follow-up, and any specific instructions or precautions for the patient.

Dermoscopy of facial (non-scalp areas) DLE reveals several different features according to the stage of the disease and location of skin lesions (non-scalp vs. scalp). According to one prior literature review⁵, the most common findings in scalp DLE are follicular keratotic plugs, followed by absent follicular ostia and fibrotic white, yellow, black, and red dots. In contrast, the most common dermoscopic features of the follicular openings in non-scalp DLE lesions were keratotic plugs, red dots, an...

Dermoscopy is a non-invasive, convenient, and real-time alternative to skin biopsy. In 1920, Saphier used dermoscopy to examine nevus and melanoma lesions and made a descriptive diagnosis based on skin color and morphology¹⁰. In 2001, the International Conference on Dermatology established unified diagnostic criteria for dermoscopy. Recently, research on digital dermoscopy has also rapidly increased. The DP method is a microscopic digital imaging technology first developed in the 21st century

The authors declare no conflicts of interests.

We thank the patient for providing written informed consent for the publication of the protocol details and images.