A 45-Year-Old Woman Comes to the Physician with a Lump

A 45-year-old woman comes to the physician with a lump on her throat that has steadily increased in size over the past 5 months. She does not have difficulties swallowing, dyspnea, or changes in voice. Examination shows a 3-cm, hard swelling on the left side of her neck that moves with swallowing. There is no cervical or axillary lymphadenopathy. The remainder of the examination shows no abnormalities. Thyroid functions tests are within the reference range. Ultrasound of the neck shows an irregular, hypoechogenic mass in the left lobe of the thyroid. Fine-needle aspiration biopsy shows a large number of follicular cells dispersed in clusters and microfollicles.  The patient undergoes right thyroid lobectomy.  Which of the following histologic findings would confirm a diagnosis of follicular thyroid carcinoma in this patient?

A) C-cell hyperplasia
B) Cells with empty appearing nuclei
C) Hürthle cells
D) Lymphocytic germinal centers
E) Multinucleated giant cells
F) Tumor capsular invasion