Early diagnosis of malignant melanoma of the skin.

About five per cent of all malignant lesions of the skin are malignant melanomas. The poor prognosis associated with this malignant lesion emphasizes the importance of early diagnosis. A large proportion of malignant melanomas arise in preexisting lesions such as junction nevi, precancerous melanoses and, much more rarely, blue nevi. Early malignant changes in these precursor lesions include increasing pigmentation, enlargement, thickening, crusting, bleeding, ulceration, tumor formation, and development of satellite lesions. Many pigmented, and some non-pigmented, lesions of the skin must be differentiated from malignant melanoma. Since even with radical surgical treatment the prognosis of malignant melanoma is poor, junction nevi which are subject to continual trauma or have signs of probable malignant degeneration should be prophylactically excised.