Syphilis Mimicking Malignant Pulmonary Tumor With Nodal and Bone Metastasis on 18 F-FDG PET/CT.

A 52-year-old man suffering left pleuritic pain underwent a chest CT showing a subpleural pulmonary nodule in the left upper lobe. Because of the possibility of a lung tumor, he was referred for 18 F-FDG PET/CT. The scan revealed FDG uptake in the pulmonary nodule, in an upper right paratracheal lymph node, and at 4 destructive bone lesions. Pathologic examination after pulmonary biopsy manifested only the presence of inflammatory cells. Further clinical history research proved risky sexual behavior with a positive syphilis serology test. A follow-up PET/CT 7 months after penicillin therapy showed a complete metabolic response of all the lesions.