Magnetic resonance imaging features of osseous manifestations of early acquired syphilis

We report the case of a 64-year-old man who initially presented with a maculopapular rash followed several weeks later by bilateral shin pain and infiltrative cutaneous lesions over the lower legs. The plain radiographs were not contributory, and the patient was referred for a whole-body bone scan, which demonstrated multifocal osseous lesions, including such lesions in the lower legs, skull and facial bones. Magnetic resonance imaging (MRI) demonstrated numerous small tibial and fibular nodular lesions involving the medullary cavity and the cortex. A diagnosis of acquired syphilis was made, based on skin biopsy. Results of serological testing were consistent with recent infection. The patient was treated with intramuscular injection of penicillin, and follow-up MRI demonstrated gradual resolution of the osseous lesions. Bone involvement is a relatively rare manifestation of early acquired syphilis. Although the plain radiographic features of the bony changes in acquired syphilis are well documented, there have been no reports of the magnetic resonance imaging findings in the appendicular skeleton.