In one patient with anal and rectal syphilis, PET demonstrated increased FDG uptake in the distal rectum, anus, and regional lymphadenopathy.[sup] In another case with oropharyngeal and gastric syphilis, PET showed increased FDG accumulation in the oropharynx and lymph nodes of the cervical regions.[sup] Two cases of secondary syphilis presented with generalized lymphadenopathy, and one of them also had asymptomatic neurosyphilis.[sup], Three cases were syphilis with pulmonary involvement,[sup],, one was syphilitic osteomyelitis,[sup] one was syphilitic aortitis,[sup] and one was syphilitic hepatitis.[sup]
In syphilitic aortitis, PET showed marked radiotracer enhancement along the ascending aortic wall or in the thoracoabdominal aorta with involvement of the brachiocephalic and left carotid arteries.[sup],,, In syphilitic thoracic aneurysm, PET showed increased glucose metabolic activity, or no enhanced uptake.[sup], PET in gummatous syphilis with adrenal gland involvement showed high uptake of FDG in lesions.[sup] Scheurkogel et al .[sup] reported a case of syphilis with liver involvement as a lesion with photopenia at the center of the mass, indicating an area of central necrosis.
Three cases with syphilitic aortitis and one case with anal and rectal syphilis were incidentally diagnosed by PET.[sup],,, There were three cases, in which PET was used to rule out paraneoplastic limbic encephalitis or malignancy.[sup],, In one case with aortic aneurysm, PET was carried out to exclude active vasculitis.[sup] In ten case reports, other diseases such as malignancy or Alzheimer's disease were first considered, until the PET findings of intensely hypermetabolic lesions, indicative of inflammatory processes, led to the suspicion of syphilis, which was then confirmed by a biopsy or serological tests.[sup],,,,,,,,,,,,,,
The majority of the case reports found that a PET scan was useful for characterizing the disease extent, especially in generalized lymphadenopathy, syphilitic aortitis, and neurosyphilis with dementia,[sup],,,,,,,,,,,,,, with the exception being cases in which the PET scan showed no pathological glucose uptake.[sup],
Probable syphilitic aortitis documented by positron emission tomography.