Positron emission tomography in well differentiated fetal adenocarcinoma of the lung.

A 47-year-old woman with a 20 pack-year history of cigarette smoking presented with a chest x-ray demonstrating a left upper lobe lung density. Computed tomography of the chest showed a 3-cm lobulated mass in the apical left upper lobe. The lesion demonstrated intense focal uptake on FDG-PET scanning. The patient underwent left upper lobectomy. Pathology demonstrated the histologic and immunohistochemical findings of a well differentiated fetal adenocarcinoma (WDFA). The intense FDG-PET uptake and abundant glycogen stores associated with WDFA may be the result of its embryonic derivation and differential expression of glucose transporter proteins.