Undifferentiated thyroid cancer often appears on ultrasound as a large, diffuse swelling of the thyroid gland on both sides, with uneven density and no obvious envelope, and irregular shape, and in some cases, small foci of calcification. The goiter often invades the surrounding tissues, especially the surrounding trachea, and the patient may have difficulty breathing. In addition to swelling on the thyroid gland, undifferentiated carcinoma often presents with metastases in the lymph nodes of the neck, which are typically characterized by small calcifications in the lymph nodes and cystic changes in some or all of them. These enlarged lymph nodes are often large and metastatic in both cervical lymph nodes.