There is extensive irregular hypocellular sclerosis, with embedded mucin filled cystic spaces and chronic inflammation.
The sclerosis results in areas of compressed epithelial islands.
Angulated islands of squamoid cells are seen, and the chronic inflammation may be quite dense.
Many eosinophils are seen admixed with the lymphocytes.
Bland appearing mucocytes line the mucin filled cysts, while some residual thyroid follicles try to persist. Luminal bright pink colloid is present within their lumens.
Strands and small nests of squamoid tumor cells exhibiting mild to moderate nuclear pleomorphism, distinct nucleoli, and pale to light pink cytoplasm comprise the neoplastic component.
These tumors are found in thyroid glands otherwise showing extensive Hashimotos thyroiditis. Hurthle cells and germinal centers are found here.
This is a rare neoplasm distinct from the usual mucoepidermoid carcinoma, and characterized by: extensive sclerosis, squamous and glandular differentiation, a concomitant inflammatory infiltrate rich in eosinophils, and a background of lymphocytic thyroiditis. The tumor is not encapsulated but tends to be well circumscribed, often with prominent lymphoid tissue that may form germinal centers at its periphery. Tumors are positive for thyroglobulin and keratin, and negative for calcitonin.
This tumor tends to arise in women between ages of 58 and 71. Presenting symptoms include a painless neck mass or cold nodule on thyroid scan.
Standardized treatment has not evolved due to the rarity of this tumor. The use of chemotherapy has not been shown to have a definitive role. Partial or complete thyroidectomy is necessary, and in some cases modified radical neck dissection.
Most cases are relatively indolent but aggressive examples with distant metastases have also been described (Shehadeh). This tumor likes to involve the adjacent perithyroidal tissues including adipose tissue and skeletal muscles, and may extend more widely into larynx, trachea,and esophagus (Shehadeh).
Sim SJ, et al. Sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid: report of two patients, one with distant metastasis, and review of the literature. Hum Pathol. 1997 Sep;28(9):1091-6.
Baloch ZW, Solomon AC, LiVolsi VA. Primary mucoepidermoid carcinoma and sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid gland: a report of nine cases. Mod Pathol. 2000 Jul;13(7):802-7.
Shehadeh NJ, et al. Sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid: a case report and review of the literature. Am J Otolaryngol. 2004 Jan-Feb;25(1):48-53.