Thyroid Radioiodine Effect 

Case 1 Female in 70’s, previous partial thyroidectomy, subsequent ? local recurrence and evidence of metastatic disease with large biopsy proven metastasis in R clavicle. Known lung metastases. One dose of I ¹³¹ 5 months previously. Block of normal looking completion thyroidectomy. This thyroid shows florid changes in keeping with Radioiodine Therapy with atypical thyroid nuclei with nuclear pleomorphism and fibrosis of the gland tissue.The nuclear changes in these cases are typically diffuse but can pose a real diagnostic challenge particularly on FNA cytology if the history of previous radioiodine therapy is not known to the reporting pathologist or cytologist.

Case 2 Male, early 40’s, known Grave’s disease now thyroidectomy.  Similar changes to case 1 above are seen , this case again showed nuclear pleomorphism, and less fibrosis than case 1 with features of Graves’ Disease treated with radio-iodine.