Radiologic investigation of thoracic metastases from unknown primary sites

When a patient presents with thoracic metastases from a tumor whose site of origin is not apparent from the initial history, physical examination, and routine laboratory studies, there is a considerable likelihood that the individual will be subjected to an extensive and frequently unrewarding series of radiologic examinations. An analysis of the "behavior" of so-called tumors of unknown origin suggests that these tumors metastasize to distant sites with a frequency that is different from the more common tumors, that is to say, those whose primary site is readily apparent. While compulsive testing should unquestionably be eschewed, certain radiologic tests are still appropriate. These studies should be supplemented, when necessary, by newer pathologic studies, primarily those that involve the rapidly developing field of immunocytochemistry.