Columnar cell variant of papillary thyroid carcinoma in an adolescent: a comprehensive histopathological, immunohistochemical, and molecular analysis.

The columnar cell variant (CCV) of papillary thyroid carcinoma (PTC) is a rare histological subtype with distinct morphological and immunohistochemical (IHC) features, which can present diagnostic challenges. We report a case of a 13-year-old girl diagnosed with CCV of PTC (CCV-PTC) following a total thyroidectomy for a solitary thyroid nodule. Histopathological (HP) examination revealed aggressive features, including vascular invasion and extrathyroidal extension. However, no metastases or recurrences were observed during six years of follow-up. This case report provides a comprehensive analysis of a rare CCV-PTC in an adolescent, focusing on its HP, IHC, and molecular characteristics. It also discusses diagnostic pitfalls and differential diagnoses that should be considered.