Otitis Externa Classification and Management

Primary Classification

The American Academy of Otolaryngology-Head and Neck Surgery classifies otitis externa into several distinct types, including acute (diffuse) otitis externa, localized otitis externa (furunculosis), chronic otitis externa, necrotizing (malignant) otitis externa, fungal otitis externa (otomycosis), and otitis externa secondary to dermatologic conditions 1, 2, 3
Localized otitis externa (furunculosis) represents an infected hair follicle on the outer third of the ear canal, with clinical findings including otalgia, otorrhea, localized tenderness, focal swelling, and pustular lesions, and is most commonly caused by Staphylococcus aureus 1, 2
Necrotizing (malignant) otitis externa is a fulminant, life-threatening infection with extension beyond the external auditory canal, primarily occurring in elderly diabetic or immunosuppressed patients, and requires long-term antimicrobial therapy with antipseudomonal coverage 4, 5

Contact dermatitis can mimic otitis externa, with nickel being the most common contact allergen, affecting approximately 10% of women with pierced ears, and neomycin causing reactions in 5% to 15% of patients with chronic external otitis 1, 2
Seborrheic dermatitis presents with greasy yellowish scaling, itching, and secondary inflammation from Malassezia yeast, and is more pronounced in patients with Down syndrome, HIV infection, and Parkinson's disease 1, 2

Herpes zoster oticus (Ramsay Hunt syndrome) causes vesicles on the external ear canal and posterior auricle, severe otalgia, facial paralysis, loss of taste on anterior two-thirds of tongue, and decreased lacrimation, and requires prompt systemic antiviral therapy and systemic steroids 1, 2

The American Academy of Otolaryngology-Head and Neck Surgery emphasizes that clinicians must distinguish diffuse acute otitis externa from other causes of otalgia, otorrhea, and inflammation before initiating treatment 6