C19
Thin relapsing melanomas: a 21-year review
Susannah Fraser1, Andrew Krajewski2, Alan Evans3, James Vestey4, Ros Rankin5, Val Doherty1
1Dept of Dermatology, Royal Infirmary of Edinburgh, Edinburgh, UK, 2Dept of Pathology, Western General Hospital, Edinburgh, UK, 3Dept of Pathology, Ninewells Hospital, Dundee, UK, 4Dept of Dermatology, Raigmore Hospital, Inverness, UK, 5Dept of Pathology, Raigmore Hospital, Inverness, UK
Thin malignant melanomas (Breslow thickness < 1 millimetre) account for around three quarters of all melanomas, and 5-year survival rates of 98% are quoted. The disease recurs in a few patients, however, leading to morbidity and mortality. Older males may be at higher risk, and pathological features like ulceration, regression and mitotic rate may be more worrying, but no definitive risk factor has been identified.
We used data collected by the Scottish Melanoma Group to review demographics and clinicopathological features of patients presenting with thin malignant melanomas (MM) in East Scotland between 1979 and 1999. A total of 1662 patients were recorded. 52 patients (3.13%) developed relapse (recurrence or death). 50% of patients with relapse were female. Average age at presentation was 49.7 years. The back and lower leg were the commonest sites of primary MM. The average Breslow thickness was 0.67mm (range 0.23-0.98mm). 86.5% were superficial spreading subtype. 2 (3.8%) exhibited ulceration and 26 (50%) of lesions showed vertical regression.
Twenty-eight patients (53.8%) developed nodal relapse. At time of final information 20 patients (38.5%) were alive. 6 patients (11.5%) were dead of unrelated causes and 26 (50%) were dead of melanoma.
While thin melanomas usually carry a good prognosis, a proportion will relapse and prove fatal. It is essential that efforts are made to improve identification of the subgroup of patients with thin lesions likely to relapse at time of presentation.
