[Approach in metastasis with unknown primary tumor]

Metastases of an occult primary malignancy are quite common (5-10%), especially in lymph nodes, lung and bone. The search for the unknown primary is an intellectual challenge. Thorough history, meticulous physical examination, and economically and carefully directed additional investigations are the best methods of detecting a treatable malignancy. Even extensive standardized work-up, using all available laboratory and imaging techniques, may miss the primary tumor quite often and unnecessarily burden patients with poor prognosis. Prognostically and therapeutically distinct subgroups must be treated differently.