Objective  To investigate the clinicopathological characteristics of poorly differentiated thyroid carcinoma (PDTC).

  Methods  The clinical and pathological features as well as the imaging findings of 12 cases of PDTC were retrospectively reviewed.

  Results  The 12 patients, 1 man and 11 women, with an average age of 53.6 years, presented with painless mass at the anterior neck. Grossly, the tumor had a nodular appearance. Histologically, the predominantly insular pattern was found in 4 tumors, the trabecular architecture in 5 tumors, and the solid flake architecture in 3 tumors. Immunohistochemically, TTF1 was positive in 11 cases. Thyroglobulin expression was noted in 10 cases. P53 immunostaining showed diffuse positivity in 4 cases and focal positivity in 3 cases. The Ki67 proliferative index ranged from 3% to 25%. Two patients died of the tumor progression 4 and 7.5 years after the surgery, respectively.

  Conclusion  PDTC is a rare disease with clinicopathological characteristics intermediate between follicular/papillary and anaplastic carcinomas.