Normal Mole

Normal Mole

Abnormal Mole

A mole is also called a nevus and multiple moles are called nevi. Nevi are usually harmless skin growths. There are three main types of nevi. Congenital nevi are present at birth and vary in size.

• Congenital nevi over time, usually after puberty, can develop malignant melanoma skin cancer. This can happen commonly in childhood for the very large congenital nevi.
• Acquired nevi are those that appear after birth. They rarely become malignant. Acquired nevi typically number less than 40 and are smaller than a pencil eraser. Acquired nevi are evenly colored with smooth even edges and symmetry of shape.
• Atypical nevi, also called dysplastic nevi, are nevi that are larger than a pencil eraser, have an odd shape, and may show more than one color. Atypical moles can turn into melanoma, and they may resemble a melanoma. A biopsy is often required to rule out melanoma. Having more than several atypical nevi is considered an independent risk factor for developing melanoma.

In adults, any mole that is changing or different appearing, regardless of the type, should be evaluated by a dermatologist. Dermatologists use a hand held, polarized light emitting magnifying device called a dermatoscope. This helps to determine if a mole should be removed or if it can be safely observed. If there is any doubt about the nature of a mole, then a biopsy is performed.