[Multiple primary lung cancer diagnosed by thoracic computed tomography; report of 2 cases].

Two cases of bilateral multiple primary lung cancers are presented. One is synchronous, and another is metachronous. Case 1: An abnormal shadow in the left lower lobe was found on the chest radiograph of 40-year-old female during a regular check-up. Chest computed tomography (CT) film showed a micronodule in the right S2. Left lower lobectomy was performed, followed by second-staged right S2 segmentectomy 1 month after the initial operation. Case 2: A 62-year-old female underwent left lower lobectomy for lung cancer in April 1997. Follow-up CT showed a nodule in right S8. In March 2000, right basal segmentectomy was performed for second lung cancer. Moreover, follow-up CT showed a nodule in right S3. Right wedge resection was performed for third lung cancer in July 2002. It is important to carefully examine a synchronous lesion before the operation of a primary lung cancer and to perform close follow-up surveillance for early detection of a metachronous lesion.