Fig. 1

(A) The tumor grew in a multinodular or lobular shape, with irregular fibrous scar formation visible in the center. The tumor involved the adipose connective tissue outside the thyroid gland, and several intra-venous tumor thrombi could be seen. (B) The tumor cells were arranged in solid large areas, with short spindle shaped cells with good consistency, high nuclear cytoplasmic ratio, and dark nuclear staining. (C) The pathological section of the patient’s rib chondrosarcoma 8 years ago showed that the tumor also shows obvious lobulated growth, destroying bone tissue, and involving soft tissue outside the bone cortex. The tumor consisted of two types of tissue components, relatively mature cartilage tissue (upper and upper right in the picture), and dense short spindle like mesenchymal components. (D) The short spindle-shaped mesenchymal component was highly similar to the morphology of the thyroid metastasis. (E) SOX9 immunohistochemistry staining shows diffuse positive signals in tumor cell nuclei. (F) NCOA2 FISH separation probe detection shows a red green signal separation in the nucleus of the tumor (arrows), indicating NCOA2 gene breakage