A 28-year-old man presents to the STI clinic with a painless ulcer on the glans penis for 3 weeks. He reports unprotected sexual contact 4 weeks ago with a partner of unknown serostatus. On examination, the ulcer has a clean base, indurated edges, and is non-tender. Regional lymph nodes are enlarged, firm, and non-tender. Serology shows positive RPR (1:32) and positive FTA-ABS. What is the most likely clinical stage of syphilis?

## Clinical Diagnosis: Primary Syphilis **Key Point:** Primary syphilis is characterized by a single painless ulcer (chancre) at the site of inoculation, appearing 3–90 days after exposure (average 21 days). ### Characteristic Features of Chancre | Feature | Description | | --- | --- | | **Appearance** | Solitary, round/oval, indurated ulcer | | **Base** | Clean, red, granulating | | **Edges** | Sharply demarcated, indurated ("rolled") | | **Pain** | Painless (distinguishes from herpes, aphthous ulcers) | | **Discharge** | Minimal, serous | | **Healing** | Spontaneous in 3–12 weeks even without treatment | ### Associated Findings in This Case **High-Yield:** Regional lymphadenopathy (inguinal in genital chancre) is **non-tender, firm, and mobile** — this is called *regional bubo* and is pathognomonic for primary syphilis. **Clinical Pearl:** The patient has **positive serology** (both RPR and FTA-ABS), confirming *Treponema pallidum* infection. RPR becomes positive 1–4 weeks after chancre appearance. ### Why Not Other Stages? - **Secondary syphilis:** Occurs 4–10 weeks after chancre appears; presents with **systemic symptoms** (fever, rash, lymphadenopathy, mucous patches, condyloma lata). This patient has a localized ulcer only. - **Early latent syphilis:** Defined as asymptomatic seropositivity within 1 year of infection; no clinical lesions present. - **Tertiary syphilis:** Occurs ≥3 years after infection; manifests as gummas, neurosyphilis, or cardiovascular syphilis. **Mnemonic:** **CHAMP** — Chancre, Hard, Asymptomatic, Minimal discharge, Primary stage. [cite:Harrison 21e Ch 195]