Dysplastic Nevus (also known as atypical nevus, melanoma-dangerous nevus, or Clark’s nevus) is a benign pigmented skin neoplasm that carries a high risk of transformation into a malignant tumor, particularly melanoma. Dysplastic nevi can appear at any age, though the likelihood increases with age. These lesions tend to be multiple, which is especially common in individuals with multiple congenital nevi, and after excessive exposure to solar or artificial ultraviolet (UV) light. Dysplastic nevi occur with equal frequency in both men and women.
The exact cause of dysplastic nevi is not fully understood. However, several predisposing factors have been identified, which may increase the likelihood of developing these skin neoplasms. These factors can make the skin more susceptible to the formation of dysplastic nevi:
The diagnosis of dysplastic nevi is based on clinical examination, which includes a visual inspection of the lesion and dermatoscopy to assess its structure and characteristics. If there is suspicion of malignant growth or if the lesion shows atypical features, a biopsy may be performed to confirm the diagnosis and rule out melanoma.
Upon visual inspection, dysplastic nevi present as a spot or slightly elevated nodule. The lesion can be symmetrical (oval, round, or elongated), or irregular in shape. The surface of the nevus may be similar to the texture of normal skin, smooth, or slightly tuberous. In some cases, the nevus may have a rough texture or show peeling.
The borders of dysplastic nevi are usually irregular, with uneven edges that can be considered an unfavorable sign. The color of the nevus can vary widely, ranging from light brown to dark brown, and may also include shades of red, pink, and even blue. The pigment distribution is often heterogeneous, with a gradual decrease in color intensity from the center to the periphery, or different shades of the same color throughout the lesion. In some cases, the nevus may have polychromatic colors, meaning it can contain several colors or their variations.
Hair growth is usually absent in the area of dysplastic nevi, but a sparse hair growth may occasionally be seen at the periphery of the lesion.
The size of a dysplastic nevus usually ranges from 10-15 mm in diameter, although larger lesions can occur. Rapid growth of the nevus is a red flag and can be a sign of potential transformation into melanoma.
On palpation, dysplastic nevi feel slightly denser than normal skin, and there are usually no subjective sensations unless the lesion has been traumatized or exposed to ultraviolet light, in which case mild itching may occur.
Dysplastic nevi can appear anywhere on the body, with no specific location, although they are often found on sun-exposed areas of the skin.
Dermatoscopic examination of dysplastic nevi typically reveals the following features:
It is important to differentiate dysplastic nevi from other pigmented skin lesions, including:
Dysplastic nevi carry a high risk of transformation into melanoma, particularly when subjected to prolonged exposure to ultraviolet radiation or chronic trauma. The risk of malignant degeneration ranges from 1% to 10%. Dysplastic nevi can sometimes transform directly into squamous cell carcinoma, with the process often progressing through a stage known as Bowen’s disease (a precursor to skin cancer).
It is essential to monitor dysplastic nevi closely because patients with multiple nevi may have an increased risk of developing other malignant skin lesions, either on the unchanged skin or near the existing nevus. This complicates the timely detection of skin cancer and the differential diagnosis of melanoma.
Dysplastic nevi are often difficult to visually differentiate from melanoma in situ (the earliest stage of melanoma). As a result, these lesions are typically removed for histological examination to confirm their benign nature. Dynamic observation may be appropriate for lesions that do not show signs of activity over time, but this should only be done under the supervision of an oncologist. The specialist will determine whether continued monitoring or removal is necessary based on the characteristics of the nevus.
Nevi that are subject to chronic trauma from clothing, jewelry, or professional activities should be removed to prevent further irritation. Dynamic monitoring involves regular photographic documentation of the lesion to track even minor changes in appearance.
Patients with multiple dysplastic nevi should undergo periodic dermatological evaluations, ideally before and after the summer months (to assess the impact of sun exposure). Keeping a map of skin neoplasms can simplify monitoring and help identify new or altered lesions.
The treatment of dysplastic nevi typically involves surgical excision using a classic scalpel or a radiofrequency scalpel. After removal, the excised tissue is examined histologically to confirm that the lesion is benign.
Destructive methods, such as laser removal or cryodestruction, are not recommended for dysplastic nevi, as they do not allow for proper histological evaluation and can obscure the detection of malignancy.
Preventing the appearance of dysplastic nevi and minimizing their risk of malignancy involves careful attention to skin care and sun protection:
Regular skin checks, timely consultation with healthcare professionals if any changes occur, and removal of potentially dangerous lesions are crucial for maintaining skin health and preventing complications.
