[A case of metachronous multiple primary lung cancers coexistent with atypical adenomatous hyperplasia].

A seventy-year-old woman was admitted for an abnormal chest shadow on a routine radiograph. She had undergone left upper lobectomy with mediastinal lymph node resection (R2a) for lung cancer (stage I), eight years before. We diagnosed this cancer as well differentiated papillary adenocarcinoma, and it coexisted with a focus of atypical adenomatous hyperplasia (AAH) in the resected material. We had been following up this patient with chest radiography, CT scanning, and tumor marker tests, but eight years after her first operation, we found a small nodular lesion in the left upper field (S6). This nodule was not diagnosed with fiberoptic bronchoscopy. Because we could not exclude primary lung cancer or intrapulmonary metastasis (eight years ago), we performed partial lung resection on the left S6 nodule. Histopathologically, the diagnosis was well differentiated papillary adenocarcinoma of the lung, coexisting with a small hyperplastic focus in the resected material. It was very difficult to diagnose whether these two cancers were metachronous multiple primary lung cancers, or one primary and its intrapulmonary metastasis. In a retrospective study, an immunohistochemical examination employing Ki-67, PCNA, p 27 and p 53 was performed in order to differentiate between metachronous multiple primary lung cancer and intrapulmonary metastasis. But we found AAH in the same resected lung eight years ago, and suggested the possibility that another small, atypical focus had developed into a malignancy. We report a case of metachronous multiple primary lung cancers and review the relevant literature.