Malignant otitis externa.

Malignant otitis externa is an invasive, potentially life-threatening infection of the external ear and skull base that requires urgent diagnosis and treatment. It affects immunocompromised individuals, particularly those who have diabetes. The most common causative agent remains Pseudomonas aeruginosa. Definitive diagnosis is frequently elusive, requiring a high index of suspicion, various laboratory and imaging modalities, and histologic exclusion of malignancy. Long-term oral antipseudomonal agents have proven effective; however, pseudomonal antibiotic resistance patterns have emerged and therefore other bacterial and fungal causative agents must be considered. Adjunctive therapies, such as aggressive debridement and hyperbaric oxygen therapy, are reserved for extensive or unresponsive cases.