The birth of dermoscopy dates to 1655, far before the emergence of dermatology as a science (Buch & Criton, 2021; Khopkar, 2020). Initially used for inspection of nail bed capillaries, the contributions of scientists over centuries have led to the evolution of dermoscopy as an independent, dynamic field of study (Buch & Criton, 2021). Today, dermoscopy is known as a practical, noninvasive, diagnostic technique used to assess the skin in detail. It involves use of a handheld device, known as a dermatoscope. These devices are widely available in a variety of styles with basic and advanced features. With training and practice, dermatoscopes allow clinicians to observe features invisible to the naked eye. These features hold both clinical and histological significance, making them important in the diagnosis and management of cutaneous diseases (Campos-do-Carmo & Ramos-e-Silva, 2008).

NONPOLARIZED VERSUS POLARIZED VERSUS HYBRID DERMATOSCOPES

The basic principle of dermoscopy is transillumination coupled with high-power magnification. Nonpolarized, polarized, and hybrid dermatoscopes are available to achieve optimal visualization. These devices range in price from just under $300 to $1,495 on average. Cost is dependent on style, size, lighting, infection prevention features, polarization, optics, battery life, camera capability, and smartphone adaptability.

Nonpolarized devices (NPDs) require what is known as interface fluid between the skin and scope lens. This medium eliminates the skin's reflective surface, thus allowing for a clearer view (Benvenuto-Andrade et al., 2007; Khopkar, 2020). Examples of interface fluids include ultrasound gel and isopropyl alcohol. NPD allows the observer to visualize structures within the outermost layer of the skin including scale, milia-like cysts, and comedo-like openings (Benvenuto-Andrade et al., 2007; Khopkar, 2020; Yelamos et al., 2019). Polarized dermatoscopes (PDs) do not require an interface fluid and are useful in viewing deeper structures within the skin such as crystalline structures, blood vessels, and dermal pigmentation (Khopkar, 2020; Yelamos et al., 2019). Finally, hybrid dermatoscopes are available. These allow the user to toggle between nonpolarized and polarized light. Toggling provides complementary information by displaying detail within the superficial and deep layers of the skin (Benvenuto-Andrade et al., 2007; Khopkar, 2020). This detail, combined with clinical context and physical assessment, can enhance diagnostic accuracy and promote clinician confidence.

Figure 1 represents the side-by-side comparison of a seborrheic keratosis viewed under PD and NPD. Note the presence of round, whitish structures that shine brightly under NPD. These structures are milia-like cysts that histologically correspond to superficial intraepidermal keratin-filled cysts (Jaimes & Marghoob, 2017). Under PD, these structures are not visible.

FIGURE 1.:

Seborrheic keratosis visualized under nonpolarized and polarized dermoscopy. Images courtesy of Dermoscopedia.

Figure 2 represents the side-by-side comparison of melanoma viewed under PD and NPD. Observe the presence of confluent blue discoloration with a white haze under NPD. Histologically, this dermoscopic structure represents superficial clustering of heavily pigmented cells and orthokeratosis (Jaimes & Marghoob, 2017). With the use of PD alone, this finding is not visualized.

FIGURE 2.:

Melanoma visualized under nonpolarized and polarized dermoscopy. Images courtesy of Dermoscopedia.

Figure 3 represents the side-by-side comparison of another melanoma viewed under PD versus an NPD. Note the presence of parallel, shiny white streaks under PD as identified by the red arrows. Histologically, these dermoscopic structures represent increased collagen at the superficial dermis (Jaimes & Marghoob, 2017). Utilizing NPD alone does not allow for this visualization.

FIGURE 3.:

Melanoma visualized under nonpolarized and polarized dermoscopy. Images courtesy of Dermoscopedia.

INDICATIONS FOR DERMOSCOPY

Dermoscopy is appropriate in any setting in which closer cutaneous examination is indicated. Patients may present in clinic with a subjective complaint such as “this spot has grown rapidly and bleeds often.” Dermoscopy can be used in this situation to enhance assessment, thus creating a more accurate differential diagnosis. This may lead to biopsy, lesion surveillance, or patient reassurance. During skin cancer screenings, or other nondermatologic physical examinations, a lesion may appear concerning on initial inspection. For example, a large and irregular black patch may be noted on a patient's back while listening to lung sounds. Dermoscopy can be used in this situation to determine if a referral or biopsy is needed. In addition, collision lesions (i.e., basal cell carcinoma and a seborrheic keratosis) can be better identified, and suspicious foci in otherwise normal-appearing lesions may be revealed (i.e., melanoma occurring within a congenital nevus) with dermoscopy (Yelemos et al., 2019). Finally, although most known for its role in lesion assessment, dermoscopy can also be applied in the setting of hair conditions (trichoscopy), cutaneous infestations (entomodermatoscopy), nail disease (onychoscopy), and inflammatory disease of the skin (inflammatoscopy).

ADVANTAGES OF DERMOSCOPY

There are benefits to dermoscopy for patients and clinicians alike. Use of this diagnostic tool helps differentiate melanocytic lesions from nonmelanocytic lesions. The term melanocytic refers to lesions that are produced by melanocytes such as acquired nevi, blue nevi, Spitz nevi, atypical nevi, and melanoma (Marghoob et al., 2013). In contrast, nonmelanocytic lesions include other pathologies such as sebaceous gland hyperplasia, squamous cell carcinoma, and clear cell acanthoma.

Dermoscopy may help differentiate benign from malignant skin lesions. When malignant lesions are identified with dermoscopy, they are often detected at much earlier stages. This presents an opportunity for early diagnosis and promotion of better patient outcomes. This benefit is particularly important in the setting of melanoma, as it accounts for most skin-cancer-related deaths. Per Marghoob et al. (2013), by integrating dermoscopy into practice, diagnostic accuracy, sensitivity, and specificity for the diagnosis of melanoma can be improved. Dr. Marghoob et al. (2013) states that primary care physicians can reduce their referral rate, or benign-to-malignant excision ratio, from 9.5 to 3.5 when trained to use dermoscopy. These providers can also improve their accuracy in identifying suspicious lesions from 54% without dermoscopy to 76%–79% (Marghoob et al., 2013).

Another advantage of dermoscopy includes the ability to monitor lesions with digital surveillance. When this is performed, photography is utilized in capturing the view displayed on dermoscopy. These images can be saved and labeled within the patient's chart for future review. This is often useful in the management of pediatric nevi or in patients who have numerous nevi. Dermoscopy is a tool that reduces unnecessary referrals and biopsies, creates an an opportunity to reduce health care spending, and promotes patient quality of life by eliminating biopsy associated complications (i.e., infection), restrictions (i.e., exercise or travel), and undesirable expectations (i.e., scarring). Other benefits of dermoscopy include the promotion of clinician confidence in their diagnoses, patient reassurance, and opportunities for patient education (Marghoob et al., 2013).

LIMITATIONS OF DERMOSCOPY

Although dermoscopy improves diagnostic accuracy, it is important to understand that it is a tool used for screening purposes only. History, clinical appearance, and lesion symptoms remain important despite dermoscopic picture alone. For this reason, it is critical to recognize that dermoscopy is not a substitution for histopathologic evaluation (Skvara et al., 2005). Biopsy with subsequent histological correlation remains the gold standard for cutaneous diagnosis (Skvara et al., 2005). It is also important to note that accuracy is user dependent. Therefore, training and continuous education are advised. Reduced diagnostic accuracy can occur if the healthcare provider does not recognize or incorrectly interprets the dermoscopic observations (Marghoob et al., 2013).

TERMINOLOGY FOR THE NOVICE DERMOSCOPIST

Dermoscopy involves the acquisition of a dermoscopic vocabulary. This article offers the basics and aims to introduce readers to this language. First, the concept of color will be reviewed. Color, perhaps a seemingly simple observation, is important for the dermoscopist to take note of. It represents the location of melanin deposition and is a clue to determining lesion type and cutaneous involvement. The colors seen with dermoscopy include black, brown, gray, blue, white, yellow, and red (Jaimes & Marghoob, 2017). Table 1 illustrates histopathological correlation to color.

TABLE 1:

Histopathological Correlation to Color

Dermoscopic Structures

Dermoscopic structures must also be understood to accurately describe and assess lesions. These structures have direct histopathologic correlations; therefore, recognition of such features must be acquired to diagnose and manage lesions Table 2 details and illustrates dermascopic structure and histopathological correlation.

TABLE 2:

Introduction to Basic Dermoscopic Structures

Dermoscopic Algorithms

Time and training are necessary to incorporate dermoscopy into clinical practice. Although an experienced dermoscopist may simultaneously appraise lesion structures quickly, new users may wish to review algorithms to triage lesions for treatment and evaluation (Wolner et al., 2018).

Two-Step Algorithm

The two-step dermoscopy algorithm is easy to follow and an outstanding resource for the novice dermoscopist. Step 1 involves deciding if the lesion is melanocytic or nonmelanocytic based on dermoscopic criteria. Step 2 of the algorithm involves further evaluation of melanocytic lesions only. On the basis of dermoscopic evaluation, one will determine whether the lesion is benign, suspicious, or malignant. The decision to then monitor, biopsy, or refer is made (Figure 4).

FIGURE 4.:

The two-step algorithm for dermoscopy. Adapted from Marghoob et al. (2017).

The Triage Amalgamated Dermoscopic Algorithm

The Triage Amalgamated Dermoscopic Algorithm (TADA) is an additional algorithm available to consider in the management and decision making of lesions (Figure 5). TADA elaborates on the previously discussed two-step algorithm. Of note, its application is for lesions on nonglabrous skin only. To utilize the TADA method, the clinician must be proficient in recognition of organized versus disorganized colors, structures, and patterns. In addition, they must be able to accurately recognize shiny white structures, vascular structures, blue–black or gray color, and ulceration (Jaimes & Marghoob, 2017). TADA Step 1 involves determining whether the lesion is undeniably benign based on clinical observation and dermoscopic assessment. Toggling between NPD and PD may be necessary to reach this conclusion. If the lesion is unequivocally benign, monitoring or reassurance can be advised. Under this circumstance the patient should be educated on the importance of self-monitoring and provider notification of changes in appearance or symptom.

FIGURE 5.: The Triage Amalgamated Dermoscopy Algorithm (TADA) for dermoscopy. Adapted from Jaimes and Marghoob (2017).

If the lesion does not meet undeniably benign criteria, the clinician will proceed to TADA Step 2. This step requires use of PD. It involves assessment of the lesion to determine if it displays an organized or disorganized pattern. In this application, disorganization refers to the asymmetric distribution of colors and structures. If in fact disorganized, the lesion should be biopsied, or the patient should be referred for expert management. If the lesion is deemed dermoscopically organized, the clinician should proceed to TADA Step 3. In TADA Step 3, the clinician must identify the presence of a starburst pattern, blue–black color, gray color, shiny white structures, white circles, a negative pigment network, vessels, or ulceration without trauma. Such findings should raise concern about malignancy, and a biopsy or referral is advised. If the lesion does not display such characteristics, short-term monitoring, long-term monitoring, or self-monitoring is acceptable (Jaimes & Marghoob, 2017). The patient should be educated on the importance of reporting changes in symptom or appearance.

Pattern Analysis

Depending on the pattern, clinicians can determine the best or most likely diagnosis. Figure 6 shows the most common patterns found in benign nevi, including intradermal nevi. Other lesions (i.e., melanoma, nonmelanoma skin cancer, seborrheic keratoses, sebaceous gland hyperplasia, angiomas) have their own unique characteristics that will not be reviewed within this article. Figure 6 describes and depicts the most common patterns found in benign nevi. To best interpret Figure 6, read left to right. Pattern description is followed by a schematic image with an example of its corresponding dermoscopic image.

FIGURE 6.: The most common patterns found in benign nevi. Adapted from Marghoob et al. (2013). Images 10, 12, 15, and 21 appear with permission from VisualDx (VisualDx.com). Images 1–3, 5, 7, 9, 11, 13, 14, 16, 18, and 20 courtesy of Dermoscopedia (Dermoscopedia.com). Images 4, 6, 8, 17, and 19 courtesy of ISIC Archive (isic-archive.com).CONCLUSION

This article has reviewed the fundamentals of dermoscopy. Although color, dermoscopic structures, and pattern analysis in benign nevi have been introduced, much remains to be learned. This article is the first of what is intended to be a series that will introduce healthcare providers to the subject of dermoscopy. Training is encouraged, and it is recommended that readers utilize other resources including books, meetings, educational websites, and clinical practice to hone their dermoscopic skills. In this issue of the Journal of the Dermatology Nurses' Association, the following are recommended resources for training:

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