BACKGROUND: Iodinated contrast-induced sialadenitis (iodide mumps) is a rare and underrecognized delayed non-allergic adverse reaction to iodinated contrast media. It is characterized by painless or painful swelling of 1 or more salivary glands, typically occurring several hours after contrast exposure.

CASE REPORT: A 75-year-old Thai woman with stage 3a chronic kidney disease was referred for contrast-enhanced chest computed tomography (CT) imaging to evaluate longstanding bronchiectasis. Because she reported a prior episode of bilateral neck and submandibular swelling shortly after intravenous contrast administration 10 years earlier, premedication with oral prednisolone was prescribed. However, with a delayed onset (16 hours) after intravenous administration of iopromide (370 mg I/mL), she developed painful bilateral submandibular swelling and returned to the hospital. Physical examination revealed firm, mildly tender bilateral submandibular swelling without overlying erythema or purulent discharge from the openings of Wharton’s ducts. No laryngeal edema or bronchospasm was observed. Ultrasonography demonstrated diffuse enlargement of both submandibular glands, with heterogeneous echotexture, increased vascularity, and mild intraglandular ductal dilatation, without evidence of sialolithiasis or abscess. Based on the characteristic sonographic findings and the temporal relationship with contrast administration, a diagnosis of recurrent iodinated contrast-induced bilateral submandibular sialadenitis after re-exposure was made. Conservative management with warm compresses and oral analgesics resulted in complete symptom resolution within 4 days.

CONCLUSIONS: Iodinated contrast-induced sialadenitis is a rare, self-limited delayed reaction to iodinated contrast media that can recur after re-exposure. Recognition of its characteristic clinical and imaging findings is important to aid diagnosis and avoid misdiagnosis and unnecessary contrast exposure, premedication, investigations, and treatment.

Keywords: Contrast Media, Iodides, mumps, Recurrence, Sialadenitis