Which of the following is the characteristic lesion of primary syphilis?

Explanation

## Primary Syphilis: The Chancre **Key Point:** The chancre is the pathognomonic lesion of primary syphilis, appearing at the site of inoculation. ### Characteristics of the Chancre | Feature | Description | |---------|-------------| | **Appearance** | Single, painless ulcer (though multiple chancres can occur) | | **Borders** | Raised, indurated, sharply demarcated | | **Base** | Clean, red, granulating; often described as "beefy red" | | **Induration** | Firm, cartilaginous consistency ("punched-out" appearance) | | **Discharge** | Minimal, serous | | **Pain** | Typically absent (painless ulcer) | | **Duration** | 3–6 weeks, heals spontaneously even without treatment | | **Location** | Site of inoculation (genitals most common, but can be extragenital) | **High-Yield:** The chancre is **painless** — this distinguishes it from herpes simplex (painful vesicles) and haemophilus ducreyi (painful pustule/ulcer in chancroid). **Clinical Pearl:** Spontaneous healing of the chancre does NOT indicate cure — the infection progresses to secondary syphilis if untreated. Regional lymphadenopathy (non-suppurative, rubbery) is common. **Mnemonic:** **CHANCER** — **C**lean base, **H**ealed spontaneously, **A**painless, **N**on-suppurative nodes, **C**artilaginous induration, **E**roded ulcer, **R**aised borders. ### Differential Diagnosis | Condition | Key Distinguishing Feature | |-----------|---------------------------| | **Herpes simplex** | Painful vesicles, recurrent, viral prodrome | | **Chancroid** | Painful, purulent, suppurative nodes | | **Lymphogranuloma venereum** | Minimal ulcer, prominent inguinal nodes (buboes) | | **Granuloma inguinale** | Beefy red, painless, but bleeds easily; no nodes | [cite:Park 26e Ch 7]