Thyroid Gland Anaplastic Carcinoma

**Semantic type:** Neoplastic Process

**Definition:** A primary carcinoma of the thyroid gland composed of undifferentiated cells. The malignant cells demonstrate evidence of epithelial differentiation, either by immunohistochemistry or electron microscopic studies. Microscopically, in the majority of cases there is a mixture of spindle, epithelioid, and giant cells. The vast majority of the patients present with a rapidly enlarging neck mass. The clinical course is usually aggressive.

**Synonyms:** - ATC - Anaplastic Carcinoma of Thyroid - Anaplastic Carcinoma of Thyroid Gland - Anaplastic Carcinoma of the Thyroid - Anaplastic Carcinoma of the Thyroid Gland - Anaplastic Follicular Cell Derived Thyroid Carcinoma - Anaplastic Follicular Cell Derived Thyroid Gland Carcinoma - Anaplastic Thyroid Cancer - Anaplastic Thyroid Carcinoma - Anaplastic Thyroid Carcinoma - Anaplastic Thyroid Gland Carcinoma - Anaplastic thyroid carcinoma - Dedifferentiated Thyroid Gland Carcinoma - Metaplastic Thyroid Gland Carcinoma - Pleomorphic Thyroid Gland Carcinoma - Sarcomatoid Thyroid Gland Carcinoma - Thyroid Gland Carcinosarcoma - Thyroid Gland Giant Cell Carcinoma - Thyroid Gland Metaplastic Carcinoma - Thyroid Gland Pleomorphic Carcinoma - Thyroid Gland Sarcomatoid Carcinoma - Thyroid Gland Spindle Cell Carcinoma - Thyroid Gland Undifferentiated (Anaplastic) Carcinoma - Undifferentiated (Anaplastic) Thyroid Gland Cancer - Undifferentiated (Anaplastic) Thyroid Gland Carcinoma - Undifferentiated Carcinoma of Thyroid - Undifferentiated Carcinoma of Thyroid Gland - Undifferentiated Carcinoma of the Thyroid - Undifferentiated Carcinoma of the Thyroid Gland - Undifferentiated Thyroid Carcinoma - Undifferentiated Thyroid Gland Carcinoma - Undifferentiated Thyroid Tumor - anaplastic thyroid cancer