To the Editor:Melanocytic nevi are a common benign tumor disease in dermatology and can occur in all ages and parts of the skin surface.There are different clinical manifestations in pigmented nevus skin lesions.It is difficult to distinguish other diseases which have similar clinical manifestations of pigmented nevus if medical diagnosis is based solely on the color,shape,or clinical experience of the lesion.Nevi are mainly divided into three categories:junctional (melanocytes confined to the epidermis only),intra-dermal (confined to the dermis only),and compound (both an epidermal and a dermal component).The relationships between these three different types of nevi and what factors contribute to the formation of one type vs.another are still unclear.[1]