Squamous cell carcinoma arising in Hashimoto's thyroiditis.

The case of a 76-year-old white woman with squamous cell carcinoma of the thyroid gland arising in a background of Hashimoto's thyroiditis is presented. Squamous cell carcinoma of the thyroid gland is a very rare and aggressive tumor, and only a few cases are reported as arising in Hashimoto's thyroiditis. Although Hashimoto's thyroiditis alone does not necessarily predispose patients to malignancy, the finding of a prominent nodule in such a patient should suggest the possibility of malignancy, and an aggressive search and treatment regimen, including surgical intervention, should be pursued.