Anaplastic Transformation of Differentiated Papillary Thyroid Carcinoma Presenting as Cauda Equina Syndrome.

BACKGROUND Papillary thyroid carcinoma is usually an indolent disease, with an almost 80% 5-year survival rate for metastatic disease. Conversely, anaplastic thyroid cancer is much more aggressive, with median overall survival rates of 4 months. CASE REPORT A 67-year-old woman presented with metastatic papillary thyroid cancer with bone metastasis, including an unstable L4 pathological fracture.