A 30-year-old female presented with erythematous papules on her soles and palms that had appeared over the past 2 months. While psoriasis was initially considered, serology testing and biopsy confirmed the diagnosis of secondary syphilis. Key indications for secondary syphilis included annular papules with fine scaling and the presence of Biette's collarette, a thin white scaling ring around the lesions.

1. Secondary syphilis F. Peral Rubio, M.D. Department of Dermatology Complejo Hospitalario Universitario, Badajoz, Spain. www.dermatoblog.com

2. Secondary syphilis 30-year-old female. The patient was referred to us for the assessment of lesions had appeared on the soles and palms 2 months previously. Erythematous 4-7-mm papules, with fine annular scaling.

8. In this case probably the principal clinical diagnosis would be psoriasis, but always be ruled by serology, and even biopsy, s ecundary syphilis, as it finally was. Secondary syphilis

9. Secondary syphilis THE KEY TO THE DIAGNOSIS Papular syphilides A thin,white scaling ring on the surface of the lesion, known as Biette's collarette, is a helpful, although it is not pathognomonic .

10. Secondary syphilis F. Peral Rubio, M.D. Department of Dermatology Complejo Hospitalario Universitario, Badajoz, Spain. www.dermatoblog.com