Vulvar Furuncle

A vulvar furuncle is a deep, painful infection of a hair follicle and the surrounding tissue, caused mainly by Staphylococcus aureus, and may evolve into an abscess.

• Several adjacent furuncles form a carbuncle.
• Risk factors are diabetes, obesity, HIV infection, shaving, friction, poor hygiene and nasal S. aureus carriage.
• Community MRSA is a growing cause.

Painful, firm, red nodule 1 to 3 cm on the labia majora or mons that becomes fluctuant, with a central pus point.

• Tenderness, local warmth, surrounding erythema, sometimes fever and inguinal lymph node enlargement.
• Differential diagnosis: Bartholin abscess, epidermal inclusion cyst, hidradenitis suppurativa, herpes genitalis, vulval abscess, folliculitis.
• Complications: abscess, cellulitis, spread to adjacent follicles, bacteraemia, scarring, recurrence.

Diagnosis is clinical, with culture of pus to guide antibiotics.

• Clinical diagnosis.
• Pus for Gram stain, culture and sensitivity, especially when MRSA is suspected.
• Random blood glucose; HIV test.
• Full blood count and temperature when systemic illness is present.
• Ultrasound to confirm a collection if the swelling is deep and not obviously fluctuant.

Drain a fluctuant lesion, give antibiotics when indicated, and prevent recurrence.

• Supportive: warm compresses 10 to 15 minutes, 4 times daily to bring the lesion to a head; keep clean and dry; do not squeeze; cotton underwear; hand washing; use a separate towel.
• Pharmacological: small furuncle without fever or surrounding cellulitis needs drainage or compresses only. For systemic signs, multiple lesions, diabetes, HIV or cellulitis give flucloxacillin 500 mg oral 6-hourly for 5 to 7 days (child 12.5 to 25 mg/kg 6-hourly, maximum 500 mg per dose). Suspected MRSA or penicillin allergy: co-trimoxazole 960 mg oral 12-hourly for 5 to 7 days (child 24 mg/kg of the combined drug 12-hourly, maximum 960 mg per dose), or clindamycin 300 mg oral 8-hourly for 5 to 7 days. Recurrent furuncles: mupirocin 2 percent intranasal twice daily for 5 days and chlorhexidine 4 percent body wash daily for 5 to 7 days. Analgesia with paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours).
• Procedures: incision and drainage of a fluctuant furuncle under 1 percent lignocaine (maximum 3 mg/kg, absolute maximum 200 mg plain); pack lightly if the cavity is large and remove the pack at 24 to 48 hours.
• Special groups: in pregnancy use flucloxacillin or clindamycin and avoid co-trimoxazole in the first trimester and doxycycline throughout. In diabetes check glucose and use insulin to keep it at 6 to 10 mmol/L.
• Red flags: fever above 38.5 degrees Celsius, spreading cellulitis, crepitus, severe pain, hypotension, immunosuppression.
• Follow-up: review at 48 hours and at 1 week; recurrent furuncles need investigation of diabetes, HIV and S. aureus carriage.