Abstract
Malignant otitis externa is a severe and rare infection of the external acoustic meatus. Triphasic bone and 67 Ga scintigraphies are used to initial detect and follow-up the response of therapy. With single photon emission computed tomography/computed tomography images, the diagnostic sensitivity is higher. We presented a case with malignant otitis externa with initial negative planar scintigraphic finding. The lesion was detected by photon emission computed tomography/computed tomography images. We concluded that the photon emission computed tomography/computed tomography should be performed routinely for patients with suspected malignant otitis externa, even without evidence of lesion on planar images.
1
Introduction
Malignant otitis externa (MOE) is a severe and rare infection of external auditory canal with most common pathogen of Pseudomonas aeruginosa . It commonly affects elderly diabetic patients and may cause life-threatening condition to skull base osteomyelitis. MOE is a clinical diagnosis from combining history, physical exam, laboratory data and image findings. Thin section computed tomography (CT) of temporal bone and magnetic resonance image (MRI) are important image modalities used in detecting osseous and soft tissue lesions resulting from MOE. Scintigraphy is another sensitive tool and can detect MOE earlier than CT or MRI . With single photon emission computed tomography/computed tomography (SPECT/CT), scintigraphy may provide more specific localization and better sensitivity in patients of MOE.
2
Case report
An 85-year-old male presented with left side otorrhea and otalgia. Otoscopic examination revealed bare bone exposure with pus in the external acoustic meatus. The triphasic bone scintigraphy was performed after intravenous injection of 777 MBq (21.0 mCi) of 99m Tc methylene diphosphonate (MDP). The planar blood pool image revealed no abnormal MDP accumulation ( Fig. 1 A ). However, SPECT/CT showed increased blood pool to left petrous part of temporal bone ( Fig. 1 C). Delayed image disclosed similar findings ( Fig. 1 B and 1 D). Subsequent Gallium-67 ( 67 Ga) inflammatory scintigraphy was performed 24 h after intravenous injection of 111 MBq (3.0 mCi) of 67 Ga citrate. SPECT/CT of 67 Ga scintigraphy disclosed a 67 Ga-avid lesion over left temporal area corresponding to bone SPECT/CT findings ( Fig. 2 B ). The planar 67 Ga scintigraphy was unremarkable ( Fig. 2 A). Biopsy of the lesion revealed only inflammatory pus cells and no evidence of malignancy was found. The patient received daily oral Levofloxacin 500 mg after the diagnosis and the symptoms recovered well after the treatments.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
