Iodide mumps

Iodide mumps is a rare adverse reaction to iodinated contrast media. Both ionic and non-ionic contrast agents can cause these reactions, but about 90% of the cases occur with the former.

Epidemiology

The incidence is unknown, but this condition is likely underdiagnosed due to limited awareness. Prompt clinical recognition is importantessential so that further unnecessary investigation and cross-sectional imaging can be avoided.

The pathophysiology is poorly understood and may be due to a hypersensitivity reaction or, more likely, the toxic accumulation of contrast in the salivary gland ducts. The salivary glands have been shown to concentrate contrast levels up to 100 times that of serum values post administration-administration. ²Contrast is excreted nearly exclusively by the kidneys, and it has been hypothesised that pre-existing renal impairment may predispose to this condition. However, although this correlation was not demonstrated in a recent meta-analysis.³

Clinical presentation

Patients can present within minutes to several days after contrast administration, with painless salivary gland swelling. The submandibular and/or parotid glands are affected, however, there is a case report of sublingual gland disease. ⁴ The presentation can be similar to calculous or infectious sialadenitis.

Radiographic features

Ultrasound is the imaging modality of choice, which can exclude an obstructing calculus and demonstrate the typically bilateral process.

The affected glands appear enlarged and hypervascular, with prominent internal hypoechoic septae. The glands may also demonstrate a thin surrounding layer of fluid. ⁵

Treatment and prognosis

This self-limiting adverse reaction is managed conservatively and usually spontaneously subsides after about 24 hours. Medications such as steroids and antihistamines have not been shown to be effective. ³