Pinna Cellulitis

Pinna cellulitis is infection of the skin and subcutaneous tissue of the external ear, usually by streptococci or Staphylococcus aureus after piercing, trauma, insect bites, otitis externa or eczema. Infection of the cartilage (perichondritis), commonly by Pseudomonas aeruginosa after cartilage piercing, must be recognised.

• Risk factors: high ear piercing, ear trauma (including boxing), burns, diabetes, HIV, eczema, ear surgery.

Hot, red, swollen, tender pinna with fever; cellulitis involves the soft tissue and the lobe, whereas perichondritis spares the lobe and has a swollen, distorted, shiny ear.

• Differential diagnosis: perichondritis, auricular haematoma, relapsing polychondritis, otitis externa, herpes zoster oticus, erysipelas, contact dermatitis (nickel), frostbite, insect bite, malignant otitis externa (diabetes), keloid.
• Complications: auricular abscess, cartilage necrosis (cauliflower ear), perichondritis, mastoiditis, bacteraemia, facial nerve involvement, malignant otitis externa in diabetes.

Clinical.

• Swab of any discharge for culture; full blood count, CRP, blood cultures if febrile; glucose.
• Otoscopy for canal and tympanic membrane; CT temporal bone if deep pain, cranial neuropathy or diabetes with severe pain (malignant otitis externa).

Cover Pseudomonas as well as Staphylococcus whenever cartilage is involved.

• Supportive: remove earrings and jewellery, warm compress, analgesia, avoid pressure on the ear, keep the ear dry.
• Pharmacological: cellulitis of the lobe or soft tissue: flucloxacillin 500 mg four times daily for 7 days (clindamycin 300 mg three times daily if allergic). Perichondritis: ciprofloxacin 500 to 750 mg twice daily for 10 to 14 days, with flucloxacillin 500 mg four times daily; severe: piperacillin tazobactam 4.5 g IV every 6 hours, or ceftazidime 2 g IV every 8 hours with flucloxacillin. Pain: paracetamol 1 g, ibuprofen 400 mg.
• Procedures: drainage of abscess or haematoma and bolster dressing; debridement of necrotic cartilage; ENT referral.
• Special groups: pregnancy, avoid ciprofloxacin and give ceftazidime or piperacillin tazobactam for perichondritis; children, avoid ciprofloxacin and use ceftazidime 50 mg/kg every 8 hours; diabetes, evaluate for malignant otitis externa.
• Red flags: cartilage involvement, facial weakness, severe ear pain at night with granulation in the canal, fever, swelling behind the ear, no response at 48 hours.
• Follow-up: review at 24 to 48 hours; ENT follow up for deformity; avoid re-piercing cartilage.