Coexistent Papillary Thyroid Carcinoma and Its Anaplastic Transformation in Cervical Lymph Node Metastasis

ABSTRACT

The transformation of papillary thyroid carcinoma (PTC) to anaplastic thyroid carcinoma (ATC) is well documented in the literature but is an exceptionally rare occurrence in metastatic foci outside the primary thyroid lesion. Even rarer is the simultaneous occurrence of PTC and ATC in the cervical lymph nodes. We report the case of an 85–year–old man who presented with a rapidly growing neck mass diagnosed as PTC. Following surgery, multiple ATC foci in the metastatic cervical lymph node were found coexisting with PTC, whereas in the thyroid, only PTC was found. This case is of high clinical significance because transformation of PTC to ATC outside the thyroid gland per se is very rare and because it suggests rapidly growing tumors in an elderly patient. The use of core needle biopsies in cases with suspected rapid tumor growth can aid in proper diagnosis, surgical decision making, and patient counselling.