Inguinal Lymphadenitis

Inguinal lymphadenitis is inflammation of the groin lymph nodes, draining the leg, foot, lower abdominal wall, perineum, anus and genitalia. Causes include skin infections of the lower limb, sexually transmitted infections (syphilis, chancroid, lymphogranuloma venereum, genital herpes, donovanosis), filariasis, tuberculosis, plague and malignancy.

• In young sexually active adults with painful unilateral nodes, STIs must be excluded.

Tender enlarged inguinal nodes, with overlying erythema or fluctuant bubo, fever.

• LGV: unilateral painful matted nodes above and below the inguinal ligament (groove sign) that suppurate; chancroid: painful ulcer with a suppurative node; syphilis: painless rubbery nodes with a chancre; herpes: tender bilateral nodes with genital vesicles; filariasis: recurrent lymphangitis, hydrocele; plague: very painful bubo with high fever.
• Differential diagnosis: femoral hernia, lymphoma, metastatic cancer (vulva, penis, anus, skin), saphenous varix, abscess, psoas abscess, hidradenitis, lipoma, tuberculous node, undescended testis.
• Complications: abscess, sinus, ulceration, lymphoedema of the genitalia, scarring, bacteraemia, infertility (genital), chronic LGV with strictures.

Examine the leg, perineum and genitals and take a sexual history.

• Swabs for gonorrhoea and chlamydia NAAT (including LGV genotyping), HSV PCR, syphilis serology, HIV test; Haemophilus ducreyi PCR where available.
• Bubo aspirate for culture, PCR, Xpert MTB/RIF; ultrasound; full blood count, CRP, blood cultures.
• Biopsy for persistent nodes to exclude lymphoma or metastasis.

Treat the source and aspirate buboes.

• Supportive: rest, scrotal or groin support, analgesia (paracetamol 1 g, ibuprofen 400 mg), no sex until treated, partner notification and treatment, HIV and STI screening, limb hygiene.
• Pharmacological: pyogenic infection from the leg: flucloxacillin 500 mg to 1 g four times daily for 7 days (clindamycin 300 to 450 mg three times daily if allergic). LGV: doxycycline 100 mg twice daily for 21 days (azithromycin 1 g weekly for 3 weeks in pregnancy). Chancroid: azithromycin 1 g single dose or ceftriaxone 250 mg IM single dose. Syphilis: benzathine benzylpenicillin 2.4 million units IM single dose. Genital herpes: aciclovir 400 mg three times daily for 7 days. Donovanosis: azithromycin 1 g weekly or 500 mg daily for 3 weeks until healed. Plague: gentamicin 5 mg/kg IV daily or doxycycline 100 mg twice daily for 10 days. Tuberculosis: isoniazid, rifampicin, pyrazinamide and ethambutol for 2 months then isoniazid and rifampicin for 4 months.
• Procedures: needle aspiration of fluctuant nodes through normal skin; do not incise buboes; excision of persistent nodes; hernia repair when relevant.
• Special groups: pregnancy, azithromycin, amoxicillin and ceftriaxone only; children, assess for abuse and treat pyogenic causes; HIV, longer therapy and monitoring.
• Red flags: irreducible groin mass (strangulated hernia), rapidly enlarging hard node, fever with prostration, skin necrosis, weight loss.
• Follow-up: review at 1 week; STI follow up and test of cure; biopsy if node persists beyond 4 weeks.