Well-differentiated fetal adenocarcinoma of the lung

We describe the case of a 43-year-old woman with a tumor shadow in the upper lobe of the left lung. The tumor was initially suspected to be a carcinoid tumor, following percutaneous needle biopsy. Subsequently, a left upper lobectomy was performed, and a well-differentiated fetal adenocarcinoma was diagnosed histologically. Unlike the biphasic epithelial and stromal features of pulmonary blastoma, it was composed solely of malignant glands of embryonal appearance.