Melanocytic dysplasia and melanoma.

A review of a series of 226 melanomas, representing 95% of the melanomas presenting in one year, has shown that 34% are associated with atypical melanocytic proliferation or melanocytic dysplasia in the adjacent skin. The dysplasia may be lentiginous, predominantly spindle-celled or non-lentiginous in pattern. These variants appear to correspond to the previously reported lesions, lentiginous and epithelioid melanocytic dysplasia and atypical melanocytic hyperplasia respectively. Some of these are referred to as dysplastic naevi. All these variants were seen in a review of 325 cases of melanocytic dysplasia. The variations are commonly seen within the same lesion and it is argued that they are variants of a single premalignant process which might best be termed melanocytic dysplasia. Melanocytic dysplasia is seen in white races, on non-exposed and exposed skin. They may be solitary as well as multiple and the majority are non-familial. Although melanocytic dysplasia may be a precursor of a large proportion of malignant melanomas it is suggested that most lesions mature into a benign intradermal melanonaevus. The behaviour of the lesions in any single patient appears to be proportional to the number and cellularity of the lesions and the strength of the family history. A diffuse mottled pattern of melanocytic dysplasia appears to have a particularly unfavourable prognosis.