I-131 uptake in a thymic cyst

A 61-year-old woman after total thyroidectomy for papillary thyroid cancer underwent I-131 therapy. Focal uptake was seen in the chest on whole body imaging. SPECT/CT delineated I-131 accumulation in an isodense mediastinal lesion which was histologically diagnosed as a thymic cyst. I-131 uptake in a thymic cyst is rare and should be included in the gamut of false-positive entities of I-131 scintigraphy. Copyright © 2010 by Lippincott Williams & Wilkins