Squamous Cell Carcinoma of the Thyroid as a Result of Anaplastic Transformation from BRAF-Positive Papillary Thyroid Cancer.

Papillary thyroid carcinoma (PTC) is the most common malignant neoplasm of the thyroid. Majority of the PTC carries an excellent prognosis. However, patients with tall cell variant (TCV) of papillary thyroid carcinoma have a worse prognosis than those with the classic variant. On the other hand, squamous cell carcinoma of the thyroid (SCT) is an unusual neoplasm thought to arise as a primary tumor or as a component of an anaplastic or undifferentiated carcinoma. We report a patient with TCV of PTC presenting years later with squamous transformation. In addition, the patient was found to have BRAF mutation. Such dedifferentiation is considered to be a rare phenomenon and has been reported only in the form of case reports in the literature. The relationship between BRAFV600E mutation and squamous cell transformation of papillary thyroid cancer is unknown at this time. Meticulous pathology is needed to identify such variants. Our patient responded to treatment with concurrent chemotherapy with carboplatin and paclitaxel along with radiation.