With the progressive increase in the use of aggressive measures to treat primary neoplastic malignancies of the human body, which with few exceptions do not result in a cure, the emergence of pulmonary metastases from extrathoracic tumors has become a major problem. These metastatic pulmonary lesions are often clinically and radiologically indistinguishable from primary lung cancers. Consequently, the diagnostic and therapeutic approach to these lesions becomes uncertain.It has been estimated that pulmonary metastases occur in approximately 30% of all extrathoracic malignancies. 1,2 The most common primary sites are the gastrointestinal or genitourinary systems. The adenocarcinomas generally are the most common cell types. 3 The interval between diagnosis and treatment of the primary tumor and the subsequent diagnosis of secondary pulmonary lesions can range from a few months to as long as 17 years. 4 In a recent review of a series of patients who had survived their primary tumors for 5 years the interval between treatment of the primary malignancy and diagnosis of the lung metastases was 0 to 7 years. 3