A 28-year-old man presents with a painless, indurated ulcer on the glans penis with a clean base and raised borders. Dark-field microscopy reveals motile spirochetes. Which is the most common site of primary syphilis in males?

Explanation

## Primary Syphilis: Site of Inoculation **Key Point:** The glans penis is the most common site of primary syphilis (chancre) in males, accounting for approximately 70% of cases. ### Anatomical Distribution in Males | Site | Frequency | Notes | |------|-----------|-------| | Glans penis | 70% | Most common; exposed surface | | Prepuce | 15% | Second most common | | Shaft of penis | 10% | Less frequent | | Scrotum | 5% | Rare | | Anus/rectum | Variable | In MSM; important epidemiologically | **Clinical Pearl:** The chancre typically appears 3–90 days (average 21 days) after inoculation. It is a solitary, painless, indurated ulcer with a clean base, raised borders, and a characteristic "punched-out" appearance. The glans, being the most exposed and frequently traumatized site during sexual contact, is the most vulnerable to initial spirochete invasion. **High-Yield:** The glans penis is the **primary inoculation site in >70% of heterosexual male cases**. This is a high-yield fact for NEET PG exams. **Mnemonic:** **GRAFT** — Glans (most common), Rectum (MSM), Anus, Frenulum, Testes (rare). ### Why Glans? - Exposed mucocutaneous surface - High vascularity - Frequent microtrauma during intercourse - Direct contact with infected secretions [cite:Park 26e Ch 32]