Unenhanced CT head and neck was performed given the patient had previous anaphylactic reaction to intravenous iodinated contrast. Ideally in cases of suspected necrotising otitis externa contrast enhanced CT should be performed in the absence of contraindication.
Images demonstrate pronounced swelling of the left external auditory meatus (EAM), pinna and periauricular soft tissue. No periauricular or subperiosteal collection was detected. Fluid is present in the left mastoid sinuses without evidence of bone erosion. Anteroinferiorly from the EAM there is marked enlargement of the left parotid gland, but without a definitive collection identified. The fat plane between the parotid gland and masticator space is obliterated. Anteriorly there is swelling of the left masseter muscle which is of low heterogeneous attenuation.
Imaging features are consistent with necrotising otitis externa with spreading infection to the parotid and masticator space. The depressed immunostatus post recent chemoradiotherapy is a risk factor to necrotising otitis externa in this patient.