Secondary malignant melanoma in lymph nodes: incidence, time of occurrence, and mortality.

During a follow-up period of six to 12 years, 15.4% of patients in the Queensland Melanoma Project (Q.M.P.) developed histologically proven secondary deposits in lymph nodes. The incidence rate in males (21%) was twice that in females (11%), but the mortality rate was similar (M., 67%; F., 61%). Thirty-two patients (2%) had positive nodes with no known primary lesion. Metastases developed in males with lesions on the foot (50%), on the thigh (29%), and on the back (22%); and in females with lesions on the lower leg (9%) and thigh (20%). About one-half of the nodes were removed at the time of treatment of the primary growth or within two months. Three-quarters were removed in the first year. However, it was found that tumour could remain dormant for more than eight years. Dormant tumours behaved in a similar aggressive fashion on regrowth as non-dormant secondaries. Nodal metastases were present in 5% of patients at the time of their first presentation with primary melanoma. Elective node dissections were done in 6% of males and 11% of females.