Syphilitic caries callosa and lymphaden granuloma on FDG PET/CT

Learning Objectives To report 2 false positive cases of syphilitic caries callosa and lymphaden granuloma on FDG PET/CT.

A right pulmonary nodule was seen in 57 yr-old man during health examination (Case 1). A 50-yr-old female had lymphadenectasis of left cervicum and right armpit for two mo (Case 2). 18F-FDG PET/CT was performed respectively to characterize nodules. In Case 1, PET-CT revealed a right pulmonary nodule with increased FDG uptake, SUVmax=5.4. Multi-lymphonodes with hypermetabolism were observed in mediastinum, cervicum, post-peritoneum, pelvic cavity, inguinal regions. A high FDG accumulation was seen at glans penis, SUV=7.31. Then it was diagnosed as caries callosa. Specific serological tests for Treponema pallidum (RPR, TPHA) were positive. Pathology of sup-clavicle and inguinal lymph puncture revealed chronic inflammation. Postoperative pathology of right pulmonary nodule revealed a bronchioalveolar carcinoma. In case 2, increasing FDG uptake was seen in intumescent lymph nodes on PET/CT, SUV=4.31~8.56. RPR and TPHA test was positive. Biopsy specimens from right armpit lymph node showed as lymphadenitis syphilitica. Concurrenty, the patient had a granulation caused by disruption of breast prosthesis in left breast with increasing FDG uptake, SUV=3.34. Syphilis is a recurrent treponematosis, and transmitted sexually or congenitally. Specific serological test for Treponema pallidum are positive. Hard chancre, infection, granuloma are manifestatuin of syphilis in different stage. Recently syphilis is uncommon, and patients often hide correlative truth. So It was missed diagnosis easily, or mimicked a cancer to increased FDG uptake. In our study, one patient had syphilitic hard chancre accompanied by lung cancer, another had syphilis lymphadenectasis accompanied granulation caused by disruption of breast prosthesis. It hints us for identify of lymphadenectasis with increased FDG uptake, not only syphilis but also syphilis accompanied by malignant tumor and/or other inflammation should be considered