Mixed columnar cell and tall cell variant of papillary carcinoma of thyroid: A case report and review of the literature

Columnar cell and tall cell carcinomas are newly described variants of papi llary thyroid carcinoma associated with aggressive clinical behaviour. Alth ough several cases of tall cell and columnar cell variants have been report ed, only a single detailed case report of a mixed tall cell and columnar ce ll variant has been described in the English-language literature. We report another such composite tumour with predominant columna cell features in an elderly female. The tumour showed extrathyroidal extension with intralumin al superior thyroid vein invasion and lymph node metastasis. DNA ploidy ana lysis showed a diploid DNA content with no increase of S-phase fraction. Im munohistochemistry showed focal positivity for p53 and Ki-67 at the infiltr ating margins of the tumour and diffuse positivity for proliferating cell n uclear antigen. The adverse clinical course warrants aggressive treatment a nd careful follow-up.