A 28-year-old man presents with a painless inguinal swelling that is matted, multilocular, and discharges through multiple sinuses. He had a small transient genital papule 3 weeks ago. Frei test was historically used for this condition. What is the etiological agent?
- A Chlamydia trachomatis serovars L1, L2, L3 ✓
- B Haemophilus ducreyi
- C Treponema pallidum
- D Herpes simplex virus type 2
Correct answer: A. Chlamydia trachomatis serovars L1, L2, L3
Explanation
Lymphogranuloma venereum (LGV) is caused by Chlamydia trachomatis serovars L1, L2, and L3. The primary lesion is a transient, painless papule or ulcer that often goes unnoticed, followed by the secondary stage characterized by inguinal lymphadenopathy (bubo) that is multilocular, matted, and may develop the 'groove sign' due to lymphadenopathy above and below Poupart's ligament. The Frei test (intradermal test using heat-killed chlamydial antigen) was the historical diagnostic test but is now obsolete.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.