[Thyroid squamous-cell carcinoma showing thymus-like element (CASTLE): a report of eight cases].

Objective: To report 8 cases of squamous-cell carcinoma showing thymus-like element (CASTLE) of the thyroid.

Methods: Clinical data and pathological sections were retrospectively reviewed.

Results: CASTLE of the thyroid differed from ordinary squamous-cell carcinoma (SCC) in that it not only presented typical squamous pattern of differentiation, but also admixed with thymic architecture, such as Hassall's corpuscles, lymphoepithelial-like structure and mature lymphocyte infiltration in the stroma. CASTLE of the thyroid and much better prognosis than that of the ordinary SCC of the thyroid with a median survival time of 10.5 year. Histogenesis of CASTLE was discussed.

Conclusion: Thyroid CASTLE is of rare occurrence. It should be distinguished from SCC of thyroid in order to treat such patients adequately.