Letter to the Editor Bilateral radioiodine uptake by the non-lactating breast of a single nulliparous woman: a case report and literature review Masoud Moslehi1, Majid Assadi2 1Department of Nuclear Medicine, Seyedoshohada Hospital, Isfahan University of Medical Sciences, Iran 2The Persian Gulf Nuclear Medicine Research Center, Bushehr University of Medical Sciences, Iran Submitted: 15 December 2010 Accepted: 28 April 2011 Arch Med Sci 2012; 8, 3: 575-577 DOI: 10.5114/aoms.2012.28592 Copyright © 2012 Termedia & Banach Corresponding author: Majid Assadi MD The Persian Gulf Nuclear Medicine Research Center Bushehr University of Medical Sciences Bushehr 3631, Iran Phone: +98-771-2580169 Fax: +98-771-2541828 E-mail: assadipoya@yahoo.com, asadi@bpums.ac.ir Whole-body I-131 scintigraphy (I-131 WBS) has been a helpful diagnostic procedure for evaluating the existence of residual thyroid bed remnants as well as possible metastasis in patients with differentiated thyroid cancer after surgery [1, 2]. In the interpretation of I-131 WBS, breast uptake may be misread as thyroid cancer lung metastasis if it occurs with an atypical pattern or is clinically unpredictable [3]. Radioiodine uptake by women who are lactating [4], have a history of previous lactation [5], hyperpro- lactinaemia [3], or a pathologic cause [1, 6-8] is well documented; however, bilateral radioiodine uptake by the non-lactating breast of single women with negative examination for galactorrhoea has rarely been reported [5]. We report a case of bilateral breast uptake on low-dose 131-I whole- body scintigraphy in a thyroid cancer patient with a negative history of breastfeeding and also negative galactorrhoea upon examination. An 18-year-old Asian woman was referred to our centre for follow-up after a near-total thyroidectomy for histologically confirmed papillary thyroid cancer with no signs of extra-thyroidal extension (stage T2N0M0). The patient had received 3700 MBq 131I one year earlier. At this time, following withdrawal from levothyroxine 4 weeks earlier (TSH > 50 mU/l; normal values: 0.2-5 mU/l) and administration of 185 MBq 131I, whole-body scintigraphy (WBS) was performed. The WBS scan was performed on a rotating digital gamma camera equipped with a high- energy all-purpose parallel-hole collimator. The WBS showed increased activity in the anterior aspect of the chest, with additional lateral projec- tions suggesting uptake by both breasts (Figure 1). Breast uptake was mild (Figure 1 A) compared with mediastinal uptake. Serum thyroglobulin (Tg) level was below 1 ng/ml. Prolactin level was within normal limits and she had no clinical history of either galactorrhoea or mastitis and was not clin- ically suspected of having a pituitary or suprasellar tumour. During 1-year follow-up, the general condition of the patient was good and also the follow-up breast ultrasonography was unremarkable. Whole-body 131I scintigraphy has been a helpful diagnostic procedure for evaluating the existence of residual thyroid bed remnants as well as possible metastases in patients with differentiated thyroid cancer after surgery [1]. Breast uptake may be misread as metastases of thyroid cancer in the lungs [3]. Radioiodine uptake by women who are lactating [4], or