Primary squamous cell carcinoma of the thyroid gland with eggshell calcification sonographic and computed tomographic findings

Primary squamous cell carcinoma (SCC) of the thyroid gland is an extremely rare neoplasm with fewer than 55 reported cases.¹ The cancer, which resembles anaplastic carcinoma, tends to be advanced at presentation, with rapid progression and a poor prognosis.² Calcification is a common finding on thyroid imaging. Microcalcification is known to be associated with thyroid malignancy³ Eggshell or peripheral calcification was once thought to be an indicator that a tumor is benign, with few exceptions. Cases of papillary cell carcinoma, anaplastic carcinoma, and follicular cell carcinoma with this calcified pattern have been reported.^3-8 However, from review of the literature in English, no thyroid SCC with eggshell calcification has been reported. Here we report a case of primary SCC of the thyroid gland with eggshell calcification and its sonographic, computed tomographic (CT), and pathologic findings.