A 49 year-old woman with anaplastic thyroid carcinoma came, for the first time, to our clinic with an enlarged supraclavicular lymph node. Ten years earlier she received a diagnosis of benign nodular goiter and has been followed up with ultrasonography, which never demonstrated any enlargement of her thyroid nodule and with fine needle aspiration biopsies (FNAB), that always proved normal. An ultrasonographic control, performed 10 months before diagnosis, showed the onset of a shell calcification all around the thyroid nodule that forbade the performance of FNAB. At initial examination in our endocrinology centre she was found to have an enlarged thyroid nodule (changing from 3.5 cm to 4.5 cm) and a supraclavicular lymph node 3 cm wide. The patient was therefore sent to the surgeon who performed a total thyroidectomy and a lymph node exenteration. The histological examination reported a thyroid anaplastic carcinoma, composed of osteoclast-like cells and large calcifications, which showed signs of local invasion and vessel infiltration; the supraclavicular lymph node proved to be a large metastasis of anaplastic thyroid cancer. Total body CT scan, bone scintigraphy and brain CT scan showed, respectively, lung, bone and brain metastasis. Postoperative chemotherapy was rapidly interrupted for acute toxicity. The patient died for lung, bone and brain metastasis, 2 months after initial examination.