CLINICOPATHOLOGIC CONFERENCE Radioiodine Uptake in the Chest

A 60-yr-old woman was diagnosed to have papillary thyroid cancer 15 yr ago. She had a thyroidectomy followed by two doses of 100 mCi (3700 MBq) of 13IIwithin 1 yr, after which she entered into remission as evidenced by negative follow-up whole-body scans and undetectable thyroglobulin levels. She presented to the outpatient clinic for her regular follow-up complaining of productive cough with white sputum of several days duration. Her physical examination was unremarkable. Lab oratory work up showed a white blood cell count of 12.9 X 109/liter (nl, 4-11) with normal differential, TSH level of 32 mill/liter (nl, 0.2-5), FT4 level of 3.7 pmole/liter (nl, 12-30) and thyroglobulin level of <5 ug/liter (nl, 2-70). Sputum culture showed normal flora. A chest radiograph was normal. A 3-mCi ( 111-MBq) 13IIdiagnostic whole-body scan showed hilar and lobar deposition of radioiodine on the 24 hr anterior and posterior ches