Incidental finding on a SPECT/CT of a retroperitoneal leiomyosarcoma imitating a hiatal hernia in 131I whole-body scan in thyroid cancer evaluation

Abstract

A 50-year-old female patient with a previous diagnosis of papillary thyroid carcinoma treated with thyroidectomy and radioiodine therapy was admitted to the hospital for her routine follow-up procedures. On her 131I whole-body scan, radioiodine accumulation in the lower mediastinum was detected. The planar images after drinking additional water showed a persistent abnormality in the lower mediastinum (Fig. 1). The patient’s detailed medical history did not reveal a previous diagnosis of hiatal hernia. However, the patient described faint gastrointestinal symptoms such as early satiety and postprandial abdominal discomfort during the last 8 months. SPECT/CT images helped to localize more precisely the uptake in the stomach, which was compressed and displaced anteriorly by a huge retroperitoneal mass located in the left hypocondrium ahead of the spleen and to the left of the stomach. The retroperitoneal mass did not display any 131I uptake (Fig. 2). An enhanced state-of-the-art CT of the chest, abdomen and pelvis confirmed the presence of a large heterogeneous contrast-enhanced retroperitoneal mass suggestive of a sarcoma without lymphatic or distant involvement (Fig. 3). Laparotomy revealed a mass of 19 cm in the omental transcavity. A complete surgical resection was performed and pathology showed a well-differentiated retroperitoneal leiomyosarcoma. Retroperitoneal sarcomas are relatively rare neoplasms that comprise approximately 10–15 percent of all soft tissue sarcomas. They occur predominantly in middle-aged individuals, although the presentation age range is broad. Leiomyosarcomas of the