Lentinginous dysplastic naevi in the elderly: a potential precursor for malignant melanoma.

Seventy-seven skin biopsies diagnosed histologically as lentiginous junctional naevi from individuals aged over 60 years were reviewed. Seventy-three specimens showed a primarily nested pattern with disordered arthitecture concentrated within the rete ridges conforming to the pathology of a lentiginous dysplastic naevus. In 28 biopsies this was combined with a melanoma in situ. The latter was reflected by a focal loss of the rete ridge system, confluent melanocytic hyperplasia and single cell invasion of the epidermis by atypical malanocytes. Four biopsies showed lentiginous junctional naevi with only isolated naevus cell nests without a disordered architecture or cellular atypia. Thirty-seven of the 57 naevi in men were located on the back in contrast to 5 of the 20 women. In women the lower limb was the most frequent site with 8 of the 20 lesions originating at this site in contrast to 1 of the 57 men. The pathological diagnosis of dysplastic lentiginous naevi in the elderly needs to be recognised as having a high association of melanoma-in-situ changes.