The great imitator secondary syphilis of bone unveiled through combination of MRI and (99mTc)-bisphosphonates SPECT/CT

Excerpt

A 66-year-old male presented with a recent-onset inflammatory pain in both shoulders. A MRI of the right shoulder revealed multiple bone foci of high signal on proton-density fat-saturated images, with acromio-clavicular joint involvement, consistent with inflammatory lesions (Fig. 1a, b). Planar bone scintigraphy (Fig. 1c) displayed multiple foci of increased technetium-99m-labeled bisphosphonates uptake, especially in the scapulae, cortex of tibias, and calvaria. On complementary SPECT/CT, these hot spots matched with small osteolytic lesions (Fig. 1d, e, f). A diagnosis of syphilitic infection was highly suspected on the characteristic bone lesions aspect and distribution. Biological investigations revealed VDRL and TPHA titers positive at 1/10240 and 1/256, respectively. The medical team decided to conduct an antibiotic test treatment based on a single intramuscular injection of long-acting penicillin with follow-up, and not to biopsy the lesions. Four months later, the patient was reassessed with both MRI and bone scintigraphy that showed regression of the lesions (Fig. 1g, h, i). Clinical symptoms improved concurrently. TPHA titer dropped to 1/4. Diagnosis of secondary syphilis was therefore confirmed.

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