Learning Objectives: Understand the similarities and differences between DFO and NOE

Background: Necrotizing otitis externa (NOE) is a severe inflammatory process effecting both soft tissue and bone. This disease is strongly associated with diabetic patients and, to a lesser extent, immunocompromised conditions. Diabetic patients are also at risk for the development of diabetic foot osteomyelitis (DFO), another inflammatory condition effecting soft tissue and bone.

Objective: compare NOE with DFO.

Methods: clinical review.

Results: Patient's characteristics and co-morbidities are similar in both entities. Similar to NOE, Pseudomonas A. is associated with DFO, particularly in warm climates. Unlike NOE, there is no role for superficial swab cultures in DFO and deep bone biopsies are recommended for the diagnosis of the offending pathogen. MRI is reported to have a higher sensitivity and specificity compared to nuclear imaging in the diagnosis of DFO and is considered to be the imaging modality of choice for final diagnosis. Recommended treatment duration is similar in both entities, however surgery is usually performed early in the course DFO and only in a minority of cases of NOE. Repeated nuclear imaging for the evaluation of treatment response is not performed in DFO and follow up consists of physical evaluation and repeated measurements of inflammatory markers.

Conclusion: Appreciation of the similarities and differences between NOE and DFO may prove valuable in improving our understanding of NOE and advancing diagnosis and management.