Well-differentiated fetal adenocarcinoma: a very uncommon malignant lung tumor.

Well-differentiated fetal adenocarcinoma (WDFA) is a very uncommon malignant tumor originating in the lung. This report describes the case of a 38-year-old woman with a WDFA treated by surgery. The malignancy is low grade and associated with a good prognosis, and so it is important for clinicians to be aware of and to identify this rare variant of adenocarcinoma.