Metastatic lung nodule diagnosed on 18F-FDG PET/CT-guided fine needle aspiration in a patient with renal cell carcinoma.

Computed tomography (CT)-guided fine-needle aspiration cytology is an essential procedure in establishing the malignant nature of either primary or metastatic lung nodules. However, false-negative findings may result from aspiration of low-cellular areas because true metabolic and cellular tumor volume cannot be identified by anatomic imaging alone. The authors describe a case of renal cell carcinoma with a lung nodule where the highly metabolic intratumoral area was demonstrated on FDG PET/CT, after which the PET/CT-guided fine-needle aspiration cytology established the malignant nature of the nodule.