Abstract :
Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma that carries a favourable prognosis. However, a small subset unfortunately shows transformation to least differentiated anaplastic carcinoma (AC) having a highly aggressive behavior. This process usually occurs within thyroid but is rare in metastatic cervical lymph node or soft tissue neck and exceedingly rare at distant sites. We report a unique case of a 75 years female who presented with anaplastic carcinoma in metastatic neck deposit with occult papillary thyroid carcinoma. To the best of our knowledge, this is the first case in the world literature having anaplastic transformation (AT) in the metastatic neck deposit, right at the presentation with a totally unnoticed PTC clinically. We present this case to emphasize that the transformation process can occur even when the differentiated malignancy in thyroid is small, insignificant or hidden and that metastasis solely can be the presenting feature which can be misleading clinically and even histopathologically. As AC is very aggressive, there is need for early and precise diagnosis & prompt therapeutic intervention.
Keyword :
Anaplastic carcinoma, Transformation, Papillary thyroid carcinoma, Dedifferentiation, Immunohistochemistry