Squamous dedifferentiation and differentiated high-grade transformation of papillary thyroid carcinoma in metastatic lymph nodes: Two cases and literature review

Although it is extremely rare, papillary thyroid carcinoma (PTC) can exhibit unexpected behavior, with the potential to transform into more lethal forms in metastatic sites. This report describes 2 cases in which PTC transformed within metastatic lymph nodes. Case 1: A 57-year-old woman with a progressively enlarging right neck mass was found on imaging to have cervical lymphadenopathy and small right thyroid nodules.

She underwent total thyroidectomy with neck dissection. Histopathology revealed metastatic PTC with squamous dedifferentiation in cervical nodes. Immunohistochemistry confirmed thyroid origin.

Case 2: A 45-year-old woman presented with right submandibular swelling. Ultrasound revealed a left thyroid nodule with suspicious cervical lymphadenopathy. She underwent total thyroidectomy with neck dissection.

Histopathology showed conventional PTC with high-grade transformation in 1 …