Challenges in the Diagnosis of Necrotizing Otitis Externa: Report of Two Cases

Introduction: Malignant otitis externa is a rare necrotizing infection of the external auditory canal mainly affecting immunocompromised individuals. Often it is associated with a poor prognosis, with high morbidity and mortality particularly when diagnosis is delayed, thus requiring a high index of suspicion. Its diagnosis is based on clinical history, physical, and laboratory examinations, but additional tests such as computed tomography (CT) of the temporal bone, magnetic resonance imaging, and bone scintigraphy are useful.

Objectives: This study presents two cases of malignant otitis externa with distinct evolution in which additional tests proved negative.

Resumed Report: The first case is a 68-year-old male diabetic patient with malignant otitis externa presenting poor evolution despite corticosteroid therapy and use of intravenous antibiotics. Temporal bone CT scan and bone scintigraphy were negative. The patient underwent biopsy and debridement of the external auditory canal to rule out malignancy. The second case is a 59-year-old diabetic female patient with terminal nephropathy, presenting with malignant otitis externa. Imaging and nuclear medicine were also negative. Patient improved significantly with oral antibiotics at a reduced dose.

Conclusion: Literature describes minor contributions from radiological examinations in the early stages, since changes appear in very advanced stages of infection. This leads to questioning the routine request of bone scintigraphy, as a means to prevent patients with a high index of suspicion but negative imaging from not receiving the appropriate treatment.