[18F-fluorodeoxyglucose positron emission tomography (FDG-PET) negative poorly differentiated adenocarcinoma of lung with mediastinal lymph node metastases].

A 58-year-old woman was referred to our hospital for further medical examination of bilateral lung nodules on the chest computed tomography. Standardized uptake valve (SUV) max of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) were negative value at both lung nodules, but positive value (3.4) at a pretracheal lymph node. The size of the small lung nodule of the left lower lobe (S9) was unchanged, but the lung nodule of the right upper lobe (S1) was gradually enlarged. By the biopsy of the right lung nodule, the poorly differentiated adenocarcinoma was diagnosed pathologically. The right upper lobectomy with mediastinal lymph node dissection was performed. The metastasis was pathologically determined for FDG-PET positive lymph node. The most important reason for negative FDG-PET at primary lesion was considered that the expression of glucose transporter 1 (GLUT-1) was very few. FDG-PET has become a useful tool in the diagnosis of the pulmonary cancer, but we should understand its limitation and diagnose carefully.