Suppurative Lymphadenitis

Suppurative lymphadenitis is bacterial infection of a lymph node that has progressed to pus formation (abscess). Staphylococcus aureus and group A streptococcus are the usual causes; mycobacteria (tuberculosis and non tuberculous), Bartonella, and anaerobes also produce suppuration.

• Commonest in children and in the cervical, axillary and inguinal groups.
• Risk factors: skin or mucosal infection in the drainage area, poor hygiene, HIV, malnutrition.

Tender, warm, enlarging node that becomes fluctuant, with overlying erythema and fever; sinus formation if untreated.

• Differential diagnosis: reactive lymphadenopathy, tuberculous cold abscess (little warmth), non tuberculous mycobacterial lymphadenitis, cat scratch disease, lymphoma, metastatic disease, branchial cyst infection, thyroglossal duct cyst, hernia, plague bubo, Kawasaki disease.
• Complications: sinus tract, spread to deep spaces, septicaemia, scarring, airway compromise (cervical), recurrent abscess.

Clinical and ultrasound.

• Ultrasound for liquefaction and extent; aspirate for Gram stain, culture, Xpert MTB/RIF, acid fast stain and cytology.
• Full blood count, CRP, blood cultures if febrile; HIV test, chest radiograph.
• Excision biopsy if aspirate is non diagnostic or the node persists.

Drain pus and give antibiotics.

• Supportive: warm compress, analgesia, hydration, hygiene, treat the primary source.
• Pharmacological: flucloxacillin 500 mg to 1 g four times daily for 7 to 10 days (children 12.5 to 25 mg/kg four times daily), or cefalexin 500 mg four times daily; amoxicillin clavulanate 625 mg three times daily for dental or anaerobic source; penicillin allergy: clindamycin 300 to 450 mg three times daily. Severe: flucloxacillin 1 to 2 g IV every 6 hours or ceftriaxone 2 g IV daily; MRSA risk: vancomycin or cotrimoxazole 960 mg twice daily. If tuberculous: isoniazid, rifampicin, pyrazinamide and ethambutol for 2 months then isoniazid and rifampicin for 4 months.
• Procedures: needle aspiration through healthy skin (repeated), or incision and drainage of large fluctuant nodes; surgical excision for non tuberculous mycobacterial nodes.
• Special groups: pregnancy, flucloxacillin or cefalexin; children, aspiration preferred; HIV, test for tuberculosis and fungal causes.
• Red flags: neck swelling with stridor, hard fixed nodes, weight loss and night sweats, nodes over 3 cm persisting beyond 4 weeks, sepsis.
• Follow-up: review at 48 to 72 hours; repeat ultrasound if recurrent; excision biopsy for persistence.