A study of thin (< 1.5 mm) malignant melanomas with poor prognosis

555 cases of malignant melanoma less than 1.5 mm in depth were studied. 30 recurred locally or metastasised during follow-up. The width and depth of excision was similar in those with and without recurrence. There were no local recurrences in tumours < 1.0 mm which had been completely excised, irrespective of the width of excision. Other variables, the size of the primary tumour (p < 0.03), the depth of uninvolved dermis deep to the lesion (p < 0.01), the Clark level (p < 0.03) and the presence of lesional regression (p < 0.001), identify a sub-group of thin melanomas which have a poor prognosis irrespective of local treatment.