Extrapulmonary tuberculosis could involve multiple organs. However, thymic tuberculosis is relatively rare. We report a 21-year-old man who was referred for an F-FDG PET/CT imaging to assess his newly detected pulmonary nodule. The images showed the pulmonary nodule had minimal activity uptake. Unexpectedly, the thymus with elevated FDG accumulation was noted. The pulmonary nodule and thymic lesion were confirmed as tuberculosis by pathology.