Acral nevus

Acral nevus is a type of melanocytic nevus (moles) that appears on the acral skin, which includes the palms, soles, and under the nails. These nevi are of particular interest in dermatology due to their location on the body, which is less commonly affected by pigmented lesions, and their potential diagnostic challenge in distinguishing them from melanoma, especially acral lentiginous melanoma, a type of skin cancer that also occurs in these areas.

Etiology and Pathogenesis

The exact cause of acral nevi, like other melanocytic nevi, is not fully understood. However, it is believed to involve a combination of genetic and environmental factors. Ultraviolet (UV) radiation, which is a well-known risk factor for various types of skin lesions, plays a less significant role in the development of acral nevi due to the lower exposure of acral areas to sunlight.

Clinical Features

Acral nevi are characterized by their location on the palms, soles, and nail beds. They can vary in color from light brown to black and may be flat or raised. Unlike other areas of the skin, acral nevi often have a distinct pattern that can be observed under dermoscopy, a tool that allows for the enhanced visualization of skin lesions. This pattern, along with the lesion's location and appearance, aids in the differentiation from malignant melanoma.

Diagnosis

The diagnosis of acral nevus primarily involves clinical examination and dermoscopy. In uncertain or suspicious cases, a biopsy may be performed to rule out malignancy. The histopathological examination of an acral nevus typically shows nests of melanocytes at the dermo-epidermal junction, similar to other types of nevi.

Treatment and Management

Most acral nevi do not require treatment and are benign. However, monitoring for changes in size, color, or shape is important as these can be signs of malignant transformation. Surgical excision may be recommended if there is a suspicion of melanoma or for cosmetic reasons.

Differential Diagnosis

The main differential diagnosis for acral nevus is acral lentiginous melanoma. Other conditions that may present similarly include plantar warts, pigmented basal cell carcinoma, and foreign body reactions.

Prognosis

The prognosis for individuals with acral nevus is generally excellent, as these lesions are benign. However, due to the potential for misdiagnosis and the serious nature of acral lentiginous melanoma, accurate diagnosis and appropriate monitoring are crucial.

Epidemiology

Acral nevi are relatively common and can occur in individuals of any age, race, or gender. However, the prevalence and characteristics of these nevi may vary among different populations.

Prevention

There are no specific measures for the prevention of acral nevi. General skin care recommendations, including the use of sunscreen and protective clothing, are advised to minimize UV exposure, although this has a more significant impact on preventing other types of skin lesions.