Dermatoscopic Characteristics of Melanoma Versus Benign Lesions and Nonmelanoma Cancers

Function

A dermoscope is a handheld device that magnifies skin structures and provides visualization through the skin's surface, allowing clinicians to view the epidermis and superficial dermis.[5][7][8] Biopsy ratios have decreased from 1:18 to 1:4 by using this tool.[5] Studies have demonstrated the economic benefits of dermoscopy, showing that it increases the sensitivity of diagnosing malignant lesions by 91%.[9] While some may argue that aggressive biopsying, despite its low sensitivity, can be justified to detect melanoma, patient concerns must be considered. Patients often have concerns about scarring, fear of undergoing a biopsy, and the risk of infection.[4] Developing proficiency in dermoscopy can increase confidence in making informed decisions about when a biopsy is necessary

Issues of Concern

While dermoscopy is highly beneficial during a patient’s skin examination, becoming proficient with the tool requires overcoming a learning curve.[4] Dermoscopy should be considered an invaluable adjunct to the naked eye examination and relevant clinical information, such as recent changes in lesion morphology.[10] Comprehensive and consistent training is essential to develop proficiency, as initial use may actually increase benign lesion biopsy rates.[4] Clinicians risk false confidence without adequate training, potentially leading to missed necessary biopsies.[11]

Clinical Significance

Dermoscopy holds significant clinical value in differentiating benign from malignant lesions, improving diagnostic accuracy and patient care. This noninvasive tool provides a detailed examination of skin lesions, leading to more informed and precise clinical decisions.

Benign Versus Malignant Lesions

To accurately differentiate between benign and malignant lesions, it is essential to understand the characteristics of benign lesions. Certain nevi exhibit distinct dermoscopic findings. For instance, Spitz nevus typically displays a "starburst" pattern, which can help distinguish it from melanoma.[12] Benign nevi generally feature a regular pigment network and uniformly shaped globules throughout the lesion (see Image. Dermoscopic Image of a Benign Nevus).[13] Blue nevi, on the other hand, often have a homogeneous blue steel color throughout the lesion.[5]

A pigment network is a reticular pattern of brown lines commonly seen in nevi and dermatofibromas.[13] Dermatofibromas Dermatofibromas typically also feature a central white patch (see Image. Dermoscopic Image of a Dermatofibroma).[13] Atypical nevi often exhibit monomorphic vessels and multiple colors, typically black, light brown, and dark brown.[10] In contrast, melanoma will show more prominent skin markings and irregular hyperpigmentation, distinguishing it from atypical nevi.[14]

Melanoma

Dermoscopy is crucial for the early diagnosis of melanoma, as it can reveal malignant features that might otherwise appear benign during a naked eye examination.[14] Key dermoscopic characteristics of melanoma include a homogeneous blue pattern, irregular globules, pseudopods at the periphery, a negative and irregular pigment network, and angulated lines.[13] These characteristics are noted to have a high odds ratio for diagnosing melanoma.[4] A homogeneous blue pattern may correlate histologically with pagetoid spread and an increased number of melanocytes.[5] Irregular globules represent nests of melanocytes observed in histology, while pseudopods can indicate melanocyte nests at the dermal-epidermal junction.[5] 

A negative pigment network is described as winding hypopigmented lines encircling elongated globules, a finding particularly associated with melanomas arising from nevi.[13][5] Histologically, this may correlate with the bridging of rete ridges.[5] An irregular pigment network is histologically observed as disorganized rete ridges.[5] Angulated lines on histology correspond to flattened dermoepidermal junctions, pagetoid spread, and the confluence of atypical melanocytes.[5]

Subtypes of melanoma: Melanoma has several subtypes, each with specific dermoscopic characteristics that aid in diagnosis. Melanoma in situ typically presents with significant pigment regression, an atypical network, angulated lines, irregular hyperpigmentation, and prominent skin markings (see Image. Dermoscopic Image of Malignant Melanoma In Situ).[14] Lentigo maligna is one of the most challenging subtypes of melanoma to diagnose, even with dermoscopy, due to its characteristics that often resemble benign lesions.[3] Characteristics of lentigo maligna include rhomboid structure, gray globules and dots, and asymmetric pigmented follicular openings.[3] The presence of gray globules, dots, and angulated lines is highly sensitive for diagnosing lentigo maligna.[14] 

In superficial spreading melanoma, the presence of an irregular network typically indicates melanoma in situ within the lesion.[5] Not only can specific subtypes of melanoma be assessed with dermoscopy, but an increasing number of studies suggest that it may also be possible to evaluate Breslow thickness using this technique.[15] A study demonstrates that increased Breslow thickness correlates with the presence of white shiny structures, a blue-gray veil, and milky red areas.[16]

Special Site Lesions

Special site lesions exhibit specific dermoscopic characteristics that help differentiate between benign and malignant lesions, especially melanoma. In acral lesions, increased pigmentation in the ridges is a strong indicator of melanoma, with a reported specificity as high as 99%. Additionally, a checklist can be used to thoroughly evaluate acral lesions. The BRAAFF checklist stands for the characteristics of irregular blotch, parallel ridges, asymmetry of structures, asymmetry of colors, parallel furrow pattern, and fibrillar pattern. Each feature is scored as irregular blotch and asymmetry of structures and colors; each adds 1 point if present, and parallel ridges add 3 points if present. Conversely, the presence of parallel furrow and fibrillar patterns each deducts 1 point if present in the lesion. A total score of 1 or more points on the BRAAFF checklist indicates a higher likelihood of melanoma.[14]

Nonpigmented Cancerous Lesions

Dermoscopy is also valuable for assessing nonpigmented cancerous lesions. Basal and squamous cell carcinomas are the 2 most common types of skin cancers. However, the dermoscopic characteristics of nonmelanoma skin cancers are generally less specific compared to properly diagnosed melanomas. A study comparing dermoscopy to naked eye examinations found that the proportion of correct diagnoses increased from 41.3% to 52.7% when using dermoscopy.[14]

Basal cell carcinoma: Dermoscopy reveals several key characteristics of basal cell carcinoma, including arborizing vessels, a maple leaf-like structure, ulceration, blue-gray globules, blue ovoid nests, and spoke wheel areas.[14] Although some features may overlap with other neoplastic lesions, the appearance of shiny white blotches and strands, particularly visible under polarized light, are more distinctive of basal cell carcinoma than other neoplasms (see Image. Dermoscopic Image of a Basal Cell Carcinoma).

Notably, superficial basal cell carcinoma typically lacks arborizing vessels and blue ovoid nests and is more likely to exhibit multiple small erosions, especially in lighter Fitzpatrick skin types. In contrast, nodular basal cell carcinoma usually exhibits arborizing vessels, blue ovoid nests, and ulceration.[4] Pigmented basal cell carcinomas are more likely to show blue ovoid nests, blue globules, and arborizing vessels.[14]

Squamous cell carcinoma: Dermoscopy reveals distinct characteristics of squamous cell carcinoma, including coiled vessels, blood spots, structureless areas, and white circles (see Image. Dermoscopic Image of a Squamous Cell Carcinoma). Well-differentiated squamous cell carcinoma typically shows blood spots, white circles, and structureless areas, which help differentiate it from actinic keratosis. In contrast, poorly differentiated squamous cell carcinoma may present with ulceration, bleeding, and a lack of scaling. Keratoacanthoma is usually characterized by a keratin plug in the center of the lesion.[14]

Other Issues

As dermoscopy is not a standalone or perfect tool, healthcare professionals must utilize the patient's clinical history in addition to the dermoscopic findings to make an accurate diagnosis. With proper training, dermoscopy can help reduce healthcare costs and increase the rate of skin cancer detection. Dermoscopy is a valuable tool for clinicians performing skin examinations, but its benefits are fully realized only when the clinician is adequately trained. Mastering dermoscopy requires practice, but the rewards are invaluable once proficiency is achieved.

Enhancing Healthcare Team Outcomes

Dermoscopy is an invaluable tool for clinicians performing thorough skin examinations. Enhancing patient-centered care, outcomes, safety, and team performance related to dermoscopy requires an interprofessional approach involving physicians, advanced practitioners, nurses, pharmacists, and other healthcare professionals.

Physicians must master dermoscopic techniques to accurately distinguish between benign and malignant lesions, guiding diagnostic decisions and treatment planning. Proper training is essential for correctly identifying the characteristics of various skin lesions under dermoscopy. Dermoscopy significantly increases specificity in differentiating benign pigmented lesions from melanoma. Although the benefits of diagnosing nonmelanoma skin cancers are slightly lower, these lesions still exhibit distinguishing dermoscopic features that aid their diagnosis. 

Advanced practitioners and nurses must develop proficiency in recognizing dermoscopic patterns and assisting with the examination process. They are also crucial in patient education and support during follow-up care. Pharmacists are essential in understanding dermoscopic procedures and offering relevant medication advice, particularly for post-biopsy care and treatment. 

An interprofessional approach is crucial for implementing evidence-based protocols for dermoscopic examinations, ensuring standardized care, and developing clear follow-up strategies for patients with identified lesions to guarantee timely management and intervention. Using checklists such as the BRAAFF algorithm for acral melanoma can significantly improve diagnostic accuracy when distinguishing malignant from benign lesions.[17][18]

Interprofessional healthcare teams can enhance the efficacy of dermoscopy in clinical practice through coordinated care efforts. This includes efficiently referring patients to oncologists when advanced care is necessary and educating patients about their skin health, the importance of follow-ups, and preventive measures.

Studies demonstrate that dermoscopy can be cost-effective by reducing unnecessary biopsies, lowering healthcare costs, and decreasing patient anxiety associated with unnecessary procedures. Fewer biopsies also result in fewer scars, thereby improving patient satisfaction. Encouraging physicians to use dermoscopy benefits both patients and the healthcare system. Strategizing dermoscopy use ensures diagnostic accuracy and optimizes patient outcomes.