Warthin's Tumor: A Diagnostic Challenge as a Metastatic Mimicker on Post-I-131 Therapy Scan.

We present a rare case with an incidental finding of Warthin's tumour demonstrating I-131 uptake on a post-therapy whole-body scan in a patient treated for thyroid cancer with total thyroidectomy. The unexpected radioiodine concentration in the parotid region raised initial concern for metastatic disease, illustrating how non-thyroidal lesions can mimic pathological findings in post-ablative imaging. This case highlights a well-recognised diagnostic challenge in nuclear medicine: false-positive I-131 uptake. Differentiating benign radioiodine-avid lesions from true metastases is critical to prevent incorrect staging, unnecessary interventions, and inappropriate management decisions in thyroid cancer follow-up.