Diagnosis, workup, and prognosis of cutaneous metastases of unknown primary origin

BACKGROUND. Metastatic cancer of unknown primary (MCUP) accounts for 5-10% of presenting oncology patients. Premorbid identification of the primary source occurs in only 20-25% of cases. A small fraction of these tumors present in the skin and are thus likely to be encountered by dermatologists and dermatologic surgeons. OBJECTIVE. To present a practical schema for the diagnosis and evaluation of patients with MCUP. METHODS. Case report and literature review. CONCLUSION. The diagnosis of MCUP is associated with a poor prognosis, with median survival rates of less than 1 year. Efforts to identify subgroups of patients with understanding of these subgroups will enable early identification of patients with treatable disease and more favorable prognoses.