Acute monoarthritis in a delayed diagnosis of syphilis patient with persistent rupioid psoriasis-like lesions

Background The incidence of syphilis is increasing in many parts of the world. Clinicians may have limited experience in the diagnosis when the clinical appearance is unusual. If early diagnosis is not made and prompt treatment not given, then the disease may remain quiescent until more serious symptoms or systemic involvement develops. Case presentation We report the first case of a delayed diagnosis of syphilis with a ten-year history of persistent rupioid psoriasis-like lesions. Acute monoarthritis and high fever together with aggravation of skin lesions led to a careful clinical examination. Skin biopsies demonstrated syphilis spirochetes on immunohistochemical stain, and syphilis serological titers were positive. Standard treatment with benzathine penicillin brought a partial and transient improvement. A complete clinical and serological resolution of the disease was achieved by a prolonged and repeated penicillin treatment combined with methylprednisolone. A 7-year follow-up of the patient proved a full recovery. Conclusion Our case highlights the fact that clinical signs of syphilis can be diverse and complicated. Unusual clinical manifestations can happen in an immunocompetent individual. Treatment strategy may need to be adjusted in a difficult case.