Nevus (Nevi – plural) is the medical term for sharply bordered pigmented spots on the skin. These lesions are commonly known as moles, birthmarks or beauty marks. Nevi are typically benign. However, malignant melanomas (a skin cancer) can arise from pre-existing nevi. When using the term most physicians are actually referring to a variant called the melanocytic nevus which is composed of melanocytes or pigment producing cells.

Diagnosis of Nevi

Clinical diagnosis of a melanocytic nevus from other nevi can be made with the naked eye or dermoscopy. Benign nevi are further differentiated from melanoma by using the ABCDE* guidelines. There are other skin tumors which can resemble a melanocytic nevus clinically, such as a seborrheic keratosis, pigmented basal cell cancer, hemangiomas, and sebaceous hyperplasia. The main concern is distinguishing between a benign nevus, a dysplastic nevus, and a melanoma. A skin biopsy is required when clinical diagnosis is insufficient or a malignancy is suspected.

dermascope1 Dermatoscope1

Two types of Dermatoscopes

ABCDE: A popular mnemonic for remembering the signs and symptoms of melanoma
Asymmetrical skin lesion.
Border of the lesion is irregular.
Color: melanomas usually have multiple colors.
Diameter: moles greater than 6 mm are more likely to be melanomas than smaller moles.
Enlarging: Enlarging or evolving