A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 30-year-old woman presents to her primary care provider complaining of intermittent fever and loss of appetite for the past 2 weeks. She is also concerned about painful genital lesions. Past medical history is noncontributory. She takes oral contraceptives and a multivitamin daily. She has had two male sexual partners in her lifetime and uses condoms inconsistently. She admits to being sexually active with 2 partners in the last 3 months and only using condoms on occasion. Today, her vitals are normal. On pelvic exam, there are red-rimmed, fluid-filled blisters over the labia minora (as seen in the photograph below) with swollen and tender inguinal lymph nodes. Which of the following is the most likely diagnosis of this patient?
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A
SyphilisIncorrect. Primary syphilis produces a single painless indurated chancre (not multiple painful vesicles) with rubbery, painless lymphadenopathy.
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B
GonorrheaIncorrect. Gonorrhea causes mucopurulent cervicitis or urethritis without vesicular genital lesions; tender inguinal lymphadenopathy with vesicles is not its presentation.
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C
Genital herpesCorrect. Painful grouped vesicles on an erythematous base with tender regional lymphadenopathy and systemic symptoms define primary genital herpes (HSV-2).
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D
TrichomoniasisIncorrect. Trichomoniasis produces frothy yellow-green discharge with vaginal pruritus and a strawberry cervix, not painful labial vesicles.
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E
ChancroidIncorrect. Chancroid (Haemophilus ducreyi) causes painful soft ulcers with ragged borders and suppurative inguinal buboes, not the grouped vesicles on an erythematous base seen with HSV.
↑ Tap an answer to reveal the reasoning
Answer: C. Painful vesicular genital lesions on an erythematous base with tender inguinal lymphadenopathy and systemic symptoms (fever, malaise) in a sexually active young woman is classic primary genital herpes (HSV-2 more often than HSV-1). The first outbreak is the most severe, with constitutional symptoms preceding lesion appearance by hours to days. Diagnosis is confirmed by PCR or viral culture of vesicle fluid; treatment with oral acyclovir, valacyclovir, or famciclovir shortens the episode.
The lesion morphology is the key: HSV produces grouped fluid-filled vesicles that ulcerate, in contrast to the painless indurated chancre of primary syphilis, the painless cervicitis/urethritis of gonorrhea, and the frothy yellow-green vaginal discharge with strawberry cervix of trichomoniasis.
Clinical pearl: painful vesicular lesions = herpes; painless ulcer = syphilis; painful ulcer with ragged edges = chancroid (H. ducreyi); painless papule progressing to bubo = LGV (C. trachomatis L1-L3).
**Why each option:**
**A.** Primary syphilis produces a single painless indurated chancre (not multiple painful vesicles) with rubbery, painless lymphadenopathy.
**B.** Gonorrhea causes mucopurulent cervicitis or urethritis without vesicular genital lesions; tender inguinal lymphadenopathy with vesicles is not its presentation.
**C.** Correct. Painful grouped vesicles on an erythematous base with tender regional lymphadenopathy and systemic symptoms define primary genital herpes (HSV-2).
**D.** Trichomoniasis produces frothy yellow-green discharge with vaginal pruritus and a strawberry cervix, not painful labial vesicles.