Introduction: Papillary thyroid carcinoma (PTC) is a differentiated thyroid carcinoma accounting for approximately 80% of all thyroid malignancies; in contrast only 12% of thyroid cancers are anaplastic. While the transformation of papillary thyroid carcinoma to the more aggressive anaplastic carcinoma represents a well known occurrence, the transformation of metastatic PTC in a distant location is an uncommon finding, but new insights from the BRAF(V600E) mutation studies could explain such an event.
Case report: We present the case of a 50 years old woman with medical history of surgically removed anaplastic axillary lymph node with 18F-FDG PET/CT which revealing increased values with high probability of malignancy only in the left thyroid lobe. Further investigations: euthyroid state and normal calcitonin; cervical regional ultrasound examination showed a hypoechogenyc mass in the left thyroid lobe which was biopsied by fine needle aspiration with malignant result (Bethesda Category IV-B IV). Total thyroidectomy was performed and histopathological evaluation revealed multicentric papillary thyroid carcinoma. The high level of postoperatory thyroglobulin was an indication for radioactive iodine ablation. The patient also started chemotherapy.
Discussion: A pertinent question would be: it was the same disease? In our case, based on the imunohistochemical phenotype and the results of the PET/CT, a diagnosis of anaplastic dedifferentiation in a axillary lymph nodes metastasis from a multicentric papillary thyroid carcinoma is the most probable diagnosis.
Keywords: papillary, dedifferentiation, anaplastic
18 - 21 May 2019
European Society of Endocrinology