Arthropod Bite-Like Eruption as Rare Presentation of Secondary Syphilis in an HIV-Infected Patient.

Secondary syphilis represents a diagnostic challenge due to its varied clinical manifestations. Co-infection with human immunodeficiency virus (HIV) adds to the diversity of the clinical presentation of syphilis. We herein report a case of secondary syphilis as an arthropod bite-like eruption in a previously undiagnosed HIV-coinfected patient. A 24-year-old homosexual male presented with multiple corticosteroid-resistant insect bite-like nodules on his trunk and bilateral arms. Skin biopsy disclosed plasma cell infiltration and positive Treponema pallidum staining. His symptoms got dramatic remission after benzathine penicillin G therapy. The presented case extends the clinical spectrum of secondary syphilis in HIV patient.