Tumour thickness and histological type in malignant melanoma in New South Wales, Australia, 1970-76.

A detailed histopathological review was made of 408 cases randomly selected from all malignant melanomata diagnosed in New South Wales, Australia, during the period 1970 to 1976. The distribution of histological types in relation to age, sex and body site was similar to those reported elsewhere. Pigmentation was also related to the histological type of the lesion. Tumour thickness was found to be strongly correlated with mitotic activity, histological type, tumour shape and lymphocytic infiltration at the centre of the lesion. Tumour thickness was also assessed in relation to the physical characteristics of the patient (age, sex and site of primary lesion). Because of the prognostic importance of tumour thickness, this objective measurement is recommended in preference to the subjective assessment of levels of invasion, and a guide to the correspondence between these two measures of severity is suggested.