False-Positive 131I Whole-Body Scan in Well-Differentiated Thyroid Cancer Patient With Respiratory Bronchiolitis

I-131 whole-body scan is performed during treatment and follow-up after radioiodine treatment to detect functioning thyroid remnant and metastatic lesions in differentiated thyroid carcinoma (DTC). False-positive scans are rare, but may cause a potential pitfall by misleading to unnecessary radiation exposure from inappropriate radioiodine treatment. We report a case of papillary thyroid cancer patient with false-positive I-131 scan in the lung due to pulmonary bronchiolitis. Clinical correlation and imaging characteristics obtained from additional SPECT/CT images are very helpful to indicate this lesion as a benign condition.