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Abstract

Syphilis is a sexually transmitted disease caused by an infection with Treponema pallidum. It remains highly prevalent in low and middle-income countries. In recent decades, its incidence has increased in high-income countries, particularly among men who have sex with men. Clinical features include a chancre—typically a painless, indurated ulcer and may accompany be regional lymphadenopathy in primary syphilis, followed by a rash, malaise in secondary syphilis, and eventual involvement of the cardiovascular and central nervous systems in tertiary syphilis. Serologic testing is essential for establishing diagnosis.  

We present a case of a 50-year-old female who came for evaluation of a rash that began one month ago. The rash initially appeared on her chest and subsequently spread to her arms, abdomen, and back. She was prescribed prednisone, which initially helped to reduce the rash, but it recurred after discontinuation of the medication.

Physical examination revealed diffuse erythematous ovoid macules and wheals scattered across the torso, arms, and legs. A punch biopsy of her rash on her arm was performed. 

Histological examination of a skin punch biopsy revealed a perivascular and periadnexal lymphocytic infiltrate within the superficial and deep dermis, admixed with plasma cells. Treponema pallidum immunostaining highlighted spirochetes within the dermis. Subsequent serologic studies were positive for Rapid Plasma Reagin and reflex Treponema pallidum particle agglutination test. The histologic and serologic findings were most consistent with secondary syphilis. 

The patient was treated with 100 mg doxycycline twice daily for 14 days and showed improvement in symptoms at the subsequent follow-up.