Longitudinal Melanonychia: How to Distinguish a Malignant Condition from a Benign One

摘要

Longitudinal melanonychia is not a rare clinical condition.It is mostly characterized by the presence of longitudinal,demarcated,and pigmented bands on the nail unit.The etiology is generally classified as melanocytic activation or melanocytic hyperplasia.Benign nail matrix nevi and malignant subungual melanoma are classified under the etiology of melanocytic hyperplasia.The manifestations of benign and malignant melanonychia present with similar clinical features,but the prognoses of these two conditions are quite different.Therefore,it is important to distinguish malignant melanoma from benign melanonychia.History,physical examination,dermoscopy,and biopsy are obtained or performed to help determine the diagnosis.Surgical excision is commonly performed in patients who are above 50 years of age,if the increase in width of the pigmented band is rapid or sudden,if the width of the band is over 5 mm,or if the border of the band becomes blurred.All excised specimens are subjected to pathological examination for final diagnosis.