False-Positive Uptake of 124I in a Laryngeal Cyst Mimicking Thyroid Remnant After Thyroidectomy and 131I Therapy for Follicular Thyroid Carcinoma

A 46-year-old woman underwent total thyroidectomy followed by I-131 therapy for follicular thyroid carcinoma stage T3 N0 M0. Eleven years after diagnosis, the patient complained about voice changes and feared recurrent disease. Follow-up I-124 PET/CT scan revealed focal uptake in the neck, in the absence of any anatomic substrate on CT. Physical examination including laryngoscopy did not show any tumor or signs of recurrent disease. MRI of the neck demonstrated an oval-shaped lesion in the right false vocal cord. The lesion was removed in toto using carbon dioxide laser. Histological examination demonstrated a benign cyst, and the patient recovered entirely.