Identification of Malignant Potentialities of Melanocytic (Pigmented) Nevus

• An attempt is made to state the clinical features by which the physician can decide whether a common pigmented mole, appropriately designated as a melanocytic nevus, should be removed. At the junction or interface between epidermis and dermis lie the melanocytes whose multiplication and extrusion into the dermis is called junctional activity. Junctional activity is considered to be a necessary prerequisite for the development of melanoma when it arises from a preexisting nevus. Polypoid, dome-shaped, sessile, and pedunculated lesions are usually free from this histological feature, but flat lesions, slightly elevated lesions, elevated lesions with pigmented halos, and verruciform lesions are likely to have junctional activity. These latter types should, if treated at all, be totally excised and examined histologically.