Tiopronin-induced reversible bilateral parotid gland enlargement in a patient with alcoholic cirrhosis

RATIONALE: Drug-induced parotid gland enlargement is uncommon, and reports associated with tiopronin are extremely rare in both domestic and international literature. The mechanism remains unclear, and its rapid onset may easily lead to misdiagnosis as allergic reactions or other salivary gland diseases. Timely recognition and management are crucial to avoid unnecessary interventions. PATIENT CONCERNS: A 63-year-old man with alcoholic cirrhosis was admitted to our department for further management. Tiopronin was administered intravenously for hepatoprotective purposes. Approximately 20 minutes after the initiation of the infusion, the patient developed painless bilateral parotid gland swelling. DIAGNOSES: Emergency drug withdrawal was carried out immediately, and an ultrasound examination demonstrated bilateral parotid gland enlargement without obvious inflammatory changes or ductal dilation, consistent with acute noninflammatory sialadenosis. INTERVENTIONS: The tiopronin infusion was discontinued promptly. No additional interventions were administered. The patient was monitored closely with serial physical examinations. OUTCOMES: During the evening ward round on the same day, a significant reduction in parotid swelling was observed. Two days later, bilateral parotid gland enlargement had nearly completely resolved without specific treatment. LESSONS: Tiopronin-induced acute parotid gland enlargement is extremely rare. This case highlights the importance of considering drug-induced sialadenosis as a differential diagnosis when acute parotid swelling occurs shortly after drug administration. Early identification and discontinuation of the suspected agent can lead to rapid resolution, avoiding unnecessary interventions. Clinicians should be aware of this potential reaction and strengthen pharmacovigilance during tiopronin use.