METASTATIC MELANOMA OF UNKNOWN PRIMARY ORIGIN SHOWS PROGNOSTIC SIMILARITIES TO REGIONAL METASTATIC MELANOMA - RECOMMENDATIONS FOR INITIAL STAGING EXAMINATIONS

BACKGROUND, Metastatic melanoma of unknown primary origin accounts for approximately 2-6% of all melanoma cases. The prognostic significance of this diagnosis is still controversial. METHODS, Of 3258 patients w ith malignant melanoma recorded during the period 1976-1996, 2.3% had metastases of unknown primary origin. Anatomic distribution, clinical stage, and survival probabilities were evaluated. RESULTS, Thirty pati ents were classified as having cutaneous or subcutaneous in-transit me tastases, and they showed a 5-year survival rate of 83%. Thirty-seven patients were classified as having lymph node metastasis, and their 5- year survival rate was 50%. Disseminated disease was diagnosed in only 8 patients, who had a median survival of 6 months. Comparison of surv ival probabilities for patients with in-transit metastases and unknown primary tumors with the probabilities for those with cutaneous primar y tumors revealed a significant advantage for the former group. No sig nificant differences were found for patients with lymph node metastasi s when those with unknown primary tumors were compared with those who had cutaneous melanomas with regional lymph node metastasis.CONCLUSION S, The clinical disease course of patients with metastatic melanoma of unknown primary origin is similar to that of patients with primary cu taneous melanoma when the same clinical stages of the disease are comp ared. Based on the assumption that the majority of regional metastases develop from completely regressed primary cutaneous melanoma, recomme ndations for initial staging examinations in patients with unknown pri mary tumors are given in this article. (C) 1997 American Cancer Societ y.