An atypical nevus is a nevus (mole) that exhibits architectural disorder and other features under the microscope that distinguish it from a routine nevus. Generally, the atypia is graded mild, intermediate, or severe. It is known that some malignant melanomas arise from a preexisting nevus and it is thought that nevi with atypia represent precursor lesions for the development of melanoma. As such, identification and complete excision of atypical nevi may prevent the development of melanoma, a potentially deadly disease. Dr. Fremling has been providing the surgical treatment of atypical nevi for over 20 years.