Primary Undifferentiated Pleomorphic Thyroid Sarcoma Presenting as Superior Vena Cava Syndrome: A Case Report

Primary thyroid sarcomas (PTS) are an incredibly uncommon type of thyroid cancer. Undifferentiated pleomorphic sarcomas of the thyroid (UPS-T) are extremely rare subtypes of thyroid sarcoma with no defined cell differentiation. Here, we report the case of a 60-year-old female with a two-year history of hypothyroidism who presented to our hospital with productive cough, dyspnea, and diffuse facial edema for two weeks. Her chest computed tomography (CT) scan revealed a large anterior mediastinal mass and multiple bilateral pulmonary nodules. Her thyroid ultrasound showed two hypoechoic nodules, while a CT-venogram of the right upper extremity showed superior vena cava and the right brachiocephalic vein obstruction, which was relieved with angioplasty. A biopsy of the anterior mediastinal mass showed poorly differentiated pleomorphic thyroid sarcoma. The patient was not a candidate for inpatient chemo- or radiotherapy because of her overall medical condition. One week later, she developed worsening respiratory failure, was intubated and transferred to the intensive care unit (ICU), where she passed away two days later.