The coexistence of anaplastic and papillary carcinomas of the thyroid: a case presentation and literature review.

Papillary carcinomas of the thyroid are the most common malignant growth affecting the thyroid, currently representing 60-65 per cent of malignant thyroid neoplasm. Although the etiology of this neoplasm is unknown, they are thought to be related to neck irradiation, adenoma transformation, and Hashimoto thyroiditis. Papillary carcinomas are usually purely papillary but occasionally have areas of histologically different neoplasm, most commonly follicular. Overall, these carcinomas represent an indolent group of neoplasm and have an excellent prognosis. The occurrence of an anaplastic area in a papillary carcinoma represents the dedifferentiation of the primary neoplasm. This is an extremely rare occurrence and is considered to have negative prognostic significance. The purpose of this presentation is to discuss an unusual clinical case of a coexisting anaplastic and papillary carcinoma of the thyroid, diagnosed by fine needle aspiration (FNA) analysis presenting in a 67-year-old African-American woman. Evaluation and treatment will be discussed.