An infrequent initial presentation for malignant melanoma is the diagnosis of metastatic disease without a history of an obvious primary lesion. Confusion exists in the literature concerning the workup, treatment, and prognosis of the unknown primary melanoma. A retrospective, computer-aided chart review of 580 consecutively registered patients with melanoma at the University Treatment Center (Tampa, FL), identified 18 patients with an unknown primary presentation. There were 10 males and 8 females with a mean age of 38.4 years. Ninety-four percent of the patients were diagnosed with metastatic disease in a nodal basin, whereas 1 patient had a resected isolated lung mass as the initial presentation. In the patients who presented after having a biopsy of a single positive node for diagnosis, more disease was recovered in the nodal basin with a formal node dissection in 59% of the patients. Actuarial survival curves were constructed for the group with unknown primary melanoma. As a control population, survival curves were constructed of the subpopulation of patients with melanoma who had a known primary and had stage III (regional nodal disease) at diagnosis. There was no difference in survival between those with known and unknown primary melanoma (p = 0.96).
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