A clinicopathological correlation of 134 stage 1 and 79 non-invasive cutaneous melanomas presenting over a decade (1984-1993) at the Mater Misericordiae Hospital, Dublin.

Abstract

In a study of malignant melanoma during the period 1984-1993, 134 (63 per cent) had invasive melanoma and in 79 (37 per cent) melanoma was confined to the epidermis (in situ). There was female predominance, F: M = 2.4 : 1, a family history of melanoma in 1.5 per cent, a mean age at diagnosis of 50 yr. Females presented a decade earlier than males on average. Over half of invasive melanomas in females occurred on lower limbs; 40 per cent of lesions in males occurred on the trunk. Almost one third of lesions in males and over two thirds in females occurred in sun exposed area. Sixty per cent of invasive lesions were of the superficial spreading type and half of all lesions were histologically thin [less than 1.5 mm vertical depth]. Surprisingly, median lesion thickness was lower in males, probably reflecting the greater frequency of nodular lesions in females compared to males (36 per cent -v- 24 per cent). The marked increase in the number of invasive melanoma patients presenting in the second half of the decade studied (treble that of the first half) probably reflects an increase in melanoma incidence. Over the decade no change in invasive melanoma type, anatomical site or histological thickness was noted, the latter suggesting a failure to diagnose melanoma at an increasingly earlier stage. An official melanoma public education programme is required, particularly as half of the patients delayed 1 yr or more before seeking medical advice. However it is encouraging that, of the invasive melanomas, 30 per cent were small (< 10 mm), 50 per cent were histologically thin and that 37 per cent of all melanomas were in situ. The melanoma-in-situ group had a similar gender ratio and mean age at diagnosis to the invasive melanoma patients but lesions were smaller, were predominantly on the head, neck and limbs with lentigo melanoma as the commonest type.