Diagnosis of Struma Ovarii in a Patient with Papillary Thyroid Carcinoma – Verification via ¹²⁴I-PET/US Fusion

Introduction

Struma ovarii is an extremely rare and mostly benign germ-cell tumor containing predominantly differentiated thyrocytes. Simultaneous presentation of thyroid cancer and benign struma ovarii is rare; only sporadic case reports have been published (C. Ghander et al. Gynecol Oncol 2006; 102: 378 – 380 and A. Jammah et al. Arq Bras Endocrinol Metabol 2011; 55: 490 – 493 and W. Macdonald et al. Clin Nucl Med 2007; 32: 380 – 382). We describe a case of an incidentally detected struma ovarii in a patient with papillary thyroid cancer (PTC), with verification by ¹²⁴I-positron emission tomography/computed tomography (PET/CT). ¹²⁴I-PET/CT has been extensively described for patients with metastatic thyroid cancer, and a few studies report also on its role in benign thyroid diseases (Freudenberg et al. Eur Radiol 2004; 14: 2092 – 2098 and Darr et al. Clin Nucl Med 2013, [epub ahead of print]). However, due to its limited spatial resolution and soft-tissue contrast, CT has disadvantages in the detection of small structures or lesions in the pelvis, where soft-tissue contrast is poor. Therefore, ultrasound (US) is more suitable for depicting pathological structures located in soft tissue.