Limfogranuloma Venereum

01Pathophysiology

Lymphogranuloma venereum (LGV) is caused by the invasive serovars (L1, L2, L3) of Chlamydia trachomatis. What distinguishes these serovars from the more common D through K serovars is their tropism for lymphatic tissue. While serovars D-K remain confined to mucosal columnar epithelial cells and cause superficial urethritis or cervicitis, the L-serovars penetrate through the mucosal barrier and travel via lymphatic drainage to regional lymph nodes.

Once inside the lymph nodes, C. trachomatis L-serovars are taken up by macrophages, where they survive intracellularly as elementary and reticulate bodies within a membrane-bound inclusion. The organism triggers a granulomatous inflammatory response with formation of stellate (star-shaped) microabscesses surrounded by epithelioid histiocytes and multinucleated giant cells. This ongoing inflammation causes progressive lymph node necrosis, suppuration, and sinus tract formation, which clinically manifests as the fluctuant, tender buboes seen in the secondary stage.

The disease progresses in three distinct stages because the pathogen moves sequentially from the inoculation site into the lymphatic system and eventually causes chronic fibrosis. In the primary stage, the organism replicates locally at the site of entry, producing a small, painless papule or ulcer that heals spontaneously. This transient lesion is often missed entirely. In the secondary stage (2 to 6 weeks later), the organism has reached the draining lymph nodes, causing the characteristic inguinal lymphadenopathy. The groove sign develops because lymph nodes both above (superficial inguinal) and below (femoral) the inguinal ligament are simultaneously inflamed, and the ligament itself creates a visible depression between the two swollen groups.

In the tertiary stage, chronic untreated infection leads to lymphatic obstruction, fibrosis, and stricture formation. In genital disease, this produces elephantiasis of the external genitalia (esthiomene). In rectal disease, chronic granulomatous inflammation causes rectal strictures and fistulae. The rectal (proctitis) variant is particularly important in current clinical practice because LGV proctitis has emerged as a significant cause of hemorrhagic proctitis among MSM populations, often mimicking inflammatory bowel disease.

02Classification and Clinical Manifestation

03Diagnostic Workup

The diagnostic approach begins with a NAAT from the site of suspected infection. For patients presenting with inguinal buboes, the ideal specimen is an aspirate from the fluctuant lymph node. For patients presenting with proctitis, a rectal swab is used. NAAT is the best initial test because it is highly sensitive, widely available, and provides rapid results.

A positive Chlamydia trachomatis NAAT does not automatically mean LGV, however. Standard chlamydia NAATs detect all serovars, including D-K which cause ordinary urogenital chlamydia. To confirm LGV, the positive specimen should be sent for genotyping to identify the L-serovar. In practice, many clinical settings begin empiric LGV treatment based on clinical presentation plus a positive NAAT while awaiting genotyping results, because genotyping is not universally available and delays in treatment risk progression.

Serology plays a supportive but not definitive role. A complement fixation titer above 1:64 raises suspicion, but cross-reactivity between chlamydial species limits its usefulness. Microimmunofluorescence is more discriminating but remains a reference laboratory test. Serology is most useful when NAAT is negative but clinical suspicion remains high.

In the proctitis variant, anoscopy or sigmoidoscopy often reveals friable, ulcerated rectal mucosa with mucopurulent exudate. This appearance closely mimics inflammatory bowel disease, so biopsy may be performed. The histologic finding of granulomatous inflammation with stellate microabscesses is characteristic and should prompt chlamydia testing even when IBD was the initial clinical suspicion.

04Management and Treatment

The cornerstone of LGV treatment is doxycycline 100 mg orally twice daily for 21 days. The extended duration (three weeks instead of the standard seven-day course used for non-LGV genital chlamydia) is critical because the L-serovars penetrate deep into lymphatic tissue where antibiotic penetration requires sustained therapeutic levels. This is one of the most commonly tested points: a vignette that describes LGV features but offers a 7-day doxycycline course as an answer choice is a deliberate trap.

For patients who cannot take doxycycline (pregnancy, allergy), erythromycin base 500 mg orally four times daily for 21 days is the recommended alternative. Azithromycin 1 g orally once weekly for three consecutive weeks has been used, but evidence supporting its equivalence to doxycycline for LGV is limited.

Management of fluctuant buboes deserves attention. When inguinal nodes are tense and fluctuant, needle aspiration should be performed to relieve pressure and prevent spontaneous rupture through the skin. Aspiration is done through intact, healthy overlying skin. Incision and drainage is contraindicated because it promotes chronic sinus tract formation and delays healing. If buboes recur after aspiration, repeat aspiration is appropriate.

All sexual partners from the preceding 60 days should be evaluated, tested, and treated. Partners should receive at minimum a standard chlamydia treatment regimen. Patients should abstain from sexual contact until they and their partners have completed therapy and symptoms have fully resolved.

In HIV-positive patients, the same doxycycline regimen is used, but clinicians should anticipate a slower clinical response. If healing is delayed, the treatment course may need to be extended beyond 21 days. Close follow-up is essential in this population.

Tertiary complications (rectal strictures, fistulae, genital elephantiasis) generally require surgical intervention after the infection itself has been treated with antibiotics.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students lose points on LGV questions is by confusing it with other genital ulcer diseases, particularly chancroid and granuloma inguinale. The names themselves are a source of confusion: "lymphogranuloma venereum" and "granuloma inguinale" sound nearly identical, but they are completely different diseases. The critical distinction is that LGV causes prominent lymphadenopathy with minimal ulceration, while granuloma inguinale (donovanosis) causes progressive ulceration with no lymphadenopathy at all.

A second common trap is the treatment duration. Students who correctly identify chlamydia as the causative organism may select a standard 7-day doxycycline course. The vignette is testing whether you recognize that LGV requires 21 days of treatment because the invasive L-serovars reside within lymphatic tissue, not superficial mucosa.

The groove sign is the highest-yield physical exam finding for LGV. When a vignette describes inguinal swelling with a visible furrow along the inguinal ligament, this is nearly pathognomonic. No other genital ulcer disease produces this finding.

Watch for the proctitis variant in MSM patients. A vignette describing a young man with rectal bleeding, tenesmus, and granulomatous inflammation on rectal biopsy may be designed to steer you toward Crohn disease. The discriminator is the acute onset in a sexually active patient, and the question will often include a positive chlamydia NAAT as the pivotal clue.

Finally, remember the bubo management rule: aspirate, never incise. This is counterintuitive because most abscesses in surgery are managed with incision and drainage. LGV buboes are the exception because incision promotes chronic sinus tracts. If a question asks about the next step for a fluctuant inguinal bubo in a patient with confirmed LGV, needle aspiration is the correct answer.