Diagnosis
The patient’s history and physical examination, including otoscopy, usually provide sufficient information for the clinician to make the diagnosis of OE. Note that a patient who is diabetic or immunocompromised with severe pain in the ear should have necrotizing OE excluded by an otolaryngologist.
Laboratory testing
Typically, laboratory studies are not needed, but they may be helpful if the patient is immunocompromised, if the usual treatment measures are ineffective, or if a fungal cause is suspected. Tests may include the following:
Gram stain and culture of any discharge from the auditory canal
Blood glucose level
Urine dipstick
Imaging studies
Imaging studies are not required for most cases of OE. However, radiologic investigation may be helpful if an invasive infection such as necrotizing (malignant) OE is suspected or if the diagnosis of mastoiditis is being considered.
Imaging modalities may include the following:
High-resolution computed tomography (CT) - Preferred; better depicts bony erosion [5]
Radionucleotide bone scanning
Gallium scanning
Magnetic resonance imaging (MRI) - Not used as often as the other modalities; may be considered secondarily or if soft-tissue extension is the predominant concern [6]