[Precursors and early forms of malignant melanomas of the skin (author's transl)].

It is sometimes difficult to recognize precursors and early forms of malignant melanoma, even in histologic sections. Atypic melanocyte hyperplasia (AMH) occurs in the epidermal part of several benign pigment cell tumours and often evoke the suspicion of beginning malignancy. Probably there are some potentials for malignant transformation in AMH. Severe atypical melanocytic hyperplasia (SMH) corresponds to the concept of "early malignancy" in the meaning of McGovern. Severe melanocytic dysplasia (SMD) in the meaning of Clark et al. stands for an intraepidermal malignant melanoma (melanoma in situ). SMD occurs in SSM and in lentigo maligna. Sometimes it is impossible to assign it to a special type of melanoma. The importance to recognize histologically the differing behaviour of proliferating melanocytes within the epidermis for diagnosis of early malignant melanoma is accentuated.