LAUSR

Rationale: Post-therapy or diagnostic whole-body radioiodine scintigraphy is widely employed to evaluate the residual, recurrence, or metastases of differentiated thyroid carcinoma because of the high sensitivity and accuracy. However, it has pitfalls. Patient concerns: We described a 63-year-old male with a history of papillary thyroid carcinoma who was referred for iodine-131 ablation therapy. The post-therapy iodine-131 whole-body images demonstrated abnormal increased uptake of the tracer in the regions of bilateral upper abdomen. Diagnoses: The single photon emission computed tomography/computed tomography (SPECT/CT) showed the abnormal 131Iactivity was corresponded to multiple irregular cystic low densities in the both kidneys on the low-dose computed tomography images, so the diagnosis of polycystic kidney disease was confirmed. Interventions and outcomes: The patient responded well to the lifestyle-based treatments. Lessons: Polycystic kidney disease was one of the etiologies of the false-positive findings in the radioiodine scintigraphy.