Cutaneous melanocytic dysplasia and malignant melanoma. A critical review

Melanocytic dysplasia refers not only to a variety of histologic changes, but is also a histologic diagnosis. Melanocytic dysplasia represents a diagnosis for those lesions in which the biologic potential cannot be determined. Histologic differences between a diagnosis of melanocytic dysplasia and malignant melanoma are detailed. The terms: borderline malignant melanoma or lesion, precancerous melanosis, active or activated nevus and atypical melanocytic hyperplasia should be abandoned. A differential diagnosis between in situ malignant melanoma and other melanin-containing in situ malignancies has been presented. All types of malignant melanoma which originate within the epidermis or epithelium have an in situ phase and show horizontal growth, and small early forms defy classification. The classification of the most common types of malignant melanoma has been revised. Although the level of invasion and tumor thickness are useful prognostic and therapeutic parameters, their determination is crude and subject to several shortcomings.