False-Positive Iodine Uptake in a Patient with Differentiated Thyroid Cancer: A Rare Case of Uptaking Bronchoceles

Special Article - Thyroid Medicine

Annals Thyroid Res. 2017; 3(1): 89-91.

False-Positive Iodine Uptake in a Patient with Differentiated Thyroid Cancer: A Rare Case of Uptaking Bronchoceles

Mele C1,2, Samà MT¹, Bisoffi AA¹, Orsini F³, Mauri MG¹, Marzullo P1,2, Aimaretti G¹ and Pagano L¹*

¹Department of Translational Medicine, University of Piemonte Orientale, Italy

²Division of General Medicine, Istituto Auxologico Italiano, Italy

³Department of Nuclear Medicine, University Hospital “Maggiore della Carità”, Italy

*Corresponding author: Pagano L, Department of Translational Medicine, University of Piemonte Orientale, Via Solaroli 17, 28100 Novara, Italy

Received: December 27, 2016; Accepted: January 23, 2017; Published: January 26, 2017

Abstract

Introduction: Radioiodine is used for diagnosis and treatment of differentiated thyroid cancer. Thyroid cells most effectively express the Sodium- Iodide Symporter (NIS), which enables iodine uptake; however, NIS is also expressed in inflamed tissues.

Methods: This is a report on a 58 year old woman with a papillary thyroid cancer and false-positive pulmonary radioiodine (131I) uptakes at the Whole Body Scan (WBS).

Case Report: Two radioiodine treatments during withdrawal of levothyroxine were performed, with evidence of pulmonary 131I uptake. A chest Computed Tomography (CT) revealed the presence of multiple acinar opacities associated with thickening of the peripheral bronchi in both lungs, showing an uptake (SUV 8.17) at the subsequent 18F-fluorodeoxyglucose positron emission tomography with CT (FDG-PET/CT). Broncho-alveolar lavage and cytological examination were compatible with inflammation, confirming the suspicion of bronchocele.

Conclusion: Several cases of unexpected 131I uptakes have been reported so far. Therefore, WBS uptake should be correlated with clinical, biochemical data and radiological imaging in order to reduce the false-positive incidence and to avoid unnecessary treatments.

Keywords: Thyroid cancer; Bronchocele; False positive; Whole body scan; Radioiodine

Introduction

Differentiated Thyroid Cancer (DTC) is usually treated with surgery, Radioiodine Ablation Therapy (RAI) and Levotiroxine Therapy (L-T4). In particular, radioiodine has been used for more than five decades for the diagnosis and treatment of patients with DTC. The efficacy of the RAI is due to the ability of the thyroid cells to concentrate iodine, owing to the expression of the Sodium-Iodide Symporter (NIS) on the thyroid cell membrane, which mediates trapping, organification, and storage of radioiodine (131I) especially in functioning thyroid tissues [1,2].

The mechanisms of NIS regulation are multiple and not fully understood. However, it has been recently observed that some of the intracellular pathways involved in its regulation are over-activated in thyroid cancer [3-5].

A considerable number of cases of false-positive radioiodine uptakes have been reported in the Literature so far [6-8].

We herein reported on a case of false-positive 131I uptake in correspondence of a bronchocele, a segment of bronchus, usually dilatated, filled with mucus and completely enclosed [9]. In addition, a summarized review of the Literature on this topic is also reported.

Case Presentation

A 58 year old woman with a multinodular goiter underwent total thyroidectomy with incidental histological detection of multifocal follicular variant of Papillary Thyroid Cancer (PTC) in the left thyroid lobe (maximum size 0.7 cm), without infiltration of the perithyroidal soft tissues. TNM classification [10] was pT1a (m), Nx, Mx.

Upon subsequent RAI with 2.59 GBq of 131I uptake was detected in correspondence of the thyroid remnant, the thyroglossal duct and in the left hemithorax (Figure 1), in the absence of detectable serum Thyroglobulin (Tg) but positive anti-Tg Antibodies (TgAb). In order to investigate the pulmonary uptake of uncertain origin, a chest Computed Tomography (CT) was performed, which revealed multiple acinar opacities associated with thickening of the peripheral bronchi in both lungs (Figure 2), as well as in correspondence of the previously observed areas of WBS uptake.