Summary Squamous cell carcinoma in the thyroid gland

We report four cases of squamous cell carcinoma in the thyroid gland in which incidence of malignant thyroid tumors is reported to be less than 1 %. Case 1 showed pure growth of squamous cell carcinoma. Cases 2 and 3 revealed coexistence of squamous cell carcinoma and papillary carcinoma. Case 4 involved lymph node metastasis of squamous cell carcinoma-like findings in the undifferentiated carcinoma in the thyroid gland. All cases were ranked as T4 because of invasion to organs including the esophagus or thyroid cartilage. In spite of extended surgery, 3 of the 4 cases died of the disease within several months after surgery. It is likely that the appearance of squamous cell carcinoma derived from the thyroid gland adversely affects the prognosis of the patients and is a prognostic factor, and an intensive treatment system as well as early diagnostic system need to be established.