Bilateral radioiodine uptake by the non-lactating breast of a single nulliparous woman: a case report and literature review

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], hyperprolactinaemia [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 wholebody 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 I 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 I, whole-body scintigraphy (WBS) was performed. The WBS scan was performed on a rotating digital gamma camera equipped with a highenergy all-purpose parallel-hole collimator. The WBS showed increased activity in the anterior aspect of the chest, with additional lateral projections 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 clini cally 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 I 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 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: [email protected], [email protected] Letter to the Editor