False-Positive 123I-Uptake Mimics Metastatic Lung Disease in a Patient With Interstitial Lung Disease Secondary to Scleroderma.

A 59-year-old woman with a history of papillary thyroid cancer status post total thyroidectomy and 131I ablation therapy presented with lower back pain and leg weakness. MRI of the lumbar spine revealed homogenously enhancing lesions at L1-L2 and L3-L4. Subsequent whole-body 123I-Na scan demonstrated significant 123I retention in the mid to distal esophagus, as well as diffuse uptake in basal segments of the lungs bilaterally. SPECT/CT of the lumbar vertebra was unremarkable. Although 123I-Na uptake often indicates metastatic recurrence, these findings were better explained by nonspecific radioiodine uptake secondary to systemic complications of the patient's underlying scleroderma.