Syphilis (The “Great Imitator”)
Caused by the spirochete Treponema pallidum, syphilis presents with distinct dermatologic findings across its clinical stages.
Key Dermatologic Stages
| Stage | Key Clinical Finding |
|---|---|
| Primary | Chancre: A solitary, painless, indurated ulcer with a clean base and raised borders. |
| Secondary | Rash: Diffuse, symmetric, maculopapular eruption involving palms and soles; also condyloma lata. |
| Tertiary | Gummas: Destructive, granulomatous lesions that can occur on skin, bone, or viscera. |
Diagnostic Pearls
- Condyloma Lata: Smooth, flat-topped, moist, wart-like lesions; highly infectious. Distinguished from Condyloma Acuminatum (HPV), which is typically more verrucous/fleshy.
- Testing: Nontreponemal tests (RPR, VDRL) are for screening/titers; Treponemal tests (FTA-ABS, TP-PA) are confirmatory.
High-Yield Exam Pearl:
- Palms and Soles: A maculopapular rash on the palms and soles should always trigger a differential, including Secondary Syphilis, Rocky Mountain Spotted Fever, and Hand-Foot-Mouth disease.
- Chancre: Remember the primary ulcer is characteristically painless; pain is more typical of chancroid (Haemophilus ducreyi), which presents with a ragged, painful ulcer and purulent base.