Metastatic Dedifferentiated Chondrosarcoma to Thyroid Gland: A Case Report.

A 54-year-old man presented with a pathologic hip fracture secondary to a right femur tumor. A reaming biopsy showed the diagnosis of dedifferentiated chondrosarcoma (DDC). In addition, the patient had a thyroid mass. Fine needle aspirate from the thyroid mass revealed numerous large fragments of cohesive spindle cells with moderate nuclear atypia and brisk mitosis, identical to the femur tumor. Immunohistochemical staining on cell blocks of thyroid aspirate showed positivity for mesenchymal markers and negativity for epithelial and thyroid markers. The metastasis of DDC to the thyroid gland is a very rare incident and has previously been described once in the literature. In this report, we describe the clinical and pathologic findings of this case.