A 35-year-old prostitute is seen in a community health care clinic. About 4 months earlier, she had a painless labial sore and swelling of a right inguinal lymph node, both of which had subsided uneventfully over a period of several weeks. About 3 weeks later she developed fever and a generalized maculopapular skin rash that involved the palms of the hands and the soles of the feet. She has also has flattened, broad-based plaques in anogenital region. The most likely diagnosis is?

**Core Concept**
The patient's symptoms, including a painless labial sore, generalized maculopapular skin rash, and anogenital plaques, suggest an infection caused by a sexually transmitted pathogen that can lead to a secondary rash and systemic symptoms.

**Why the Correct Answer is Right**
The patient's history and physical examination findings are consistent with secondary syphilis, a complication of primary syphilis infection. The painless labial sore, known as a chancre, is a hallmark of primary syphilis. The generalized maculopapular skin rash that involves the palms of the hands and the soles of the feet is a characteristic feature of secondary syphilis. The anogenital plaques are also consistent with secondary syphilis. The infection is caused by the bacterium *Treponema pallidum*.

**Why Each Wrong Option is Incorrect**
**Option A:** Herpes simplex virus (HSV) infection can cause a painful vesicular rash, not a painless labial sore or a generalized maculopapular skin rash.
**Option B:** Chlamydia trachomatis infection can cause a urethritis or cervicitis, but not the characteristic symptoms of secondary syphilis.
**Option C:** Human immunodeficiency virus (HIV) infection can cause a variety of symptoms, but the specific combination of a painless labial sore, generalized maculopapular skin rash, and anogenital plaques is not typical of HIV.

**Clinical Pearl / High-Yield Fact**
The "Rule of Nine" in syphilis states that the chancre of primary syphilis heals spontaneously within 3-6 weeks, and the rash of secondary syphilis typically resolves within 2-6 weeks with antibiotic treatment.

**Correct Answer:** D. Secondary syphilis.

✓ Correct Answer: D. Condyloma lata