FFinalistSouthampton · 2027
Sexual health
AKT · Sexual health/Bacterial STIslow yield

Lymphogranuloma venereum (LGV)

Chlamydia trachomatis serovars L1–L3 — invasive

Overview

An invasive form of chlamydia (serovars L1–3) that infects lymphatic tissue rather than just mucosa. In the UK it occurs almost exclusively in men who have sex with men, usually as a proctitis and often with HIV co-infection. The exam point: it needs 21 days of doxycycline, not 7.

Recognise

  • Primary: small PAINLESS papule/ulcer at the inoculation site (often missed)
  • Secondary: painful inguinal/femoral buboes; the "groove sign" (nodes above and below the inguinal ligament)
  • In MSM: haemorrhagic PROCTITIS — rectal pain, mucopurulent/bloody discharge, tenesmus
  • Late/untreated: fibrosis, rectal strictures, lymphoedema (genital elephantiasis)

Red flags

  • Proctitis in an MSM patient (especially HIV-positive); rectal strictures; systemic features

Differentials & how to tell them apart

Chlamydiaordinary genital chlamydia is serovars D–K and needs only 7 days doxycycline — LGV is L1–3 and needs 21 days
Inflammatory bowel diseaseLGV proctitis mimics IBD in MSM — NAAT/biopsy distinguish
Chancroidpainful ulcer + suppurative nodes, H. ducreyi
Syphilispainless chancre but serology positive; no proctitis/groove sign

Investigations

Chlamydia NAAT on the affected site (rectal/ulcer/urethral); a positive result is sent for LGV-specific genotyping (serovars L1–3). Test for HIV and other STIs.

Management

Doxycycline 100 mg BD for 21 days

  1. 1Refer to GUM. First-line: doxycycline 100 mg BD for 21 days.Gate: Doxycycline contraindicated (pregnancy/breastfeeding) → erythromycin 500 mg QDS for 21 days
  2. 2In MSM with proctitis + positive rectal chlamydia, treat empirically for LGV while genotyping is awaited.
Doxycycline — first-line: 100 mg BD for 21 DAYS (three weeks — longer than ordinary chlamydia)
Erythromycin — alternative / pregnancy: 500 mg QDS for 21 days

Key points

The key discriminator from ordinary chlamydia: serovars L1–3 and a 21-day (not 7-day) doxycycline course. Almost always MSM and frequently HIV co-infected in the UK.

Monitor & prognosis

Symptom resolution; test of cure where indicated; full HIV/STI screen.

Excellent if treated early; late fibrosis/strictures if missed.

Source: BASHH LGV guideline; NICE CKS Chlamydia