Thyroid cancer. Light micrograph of a section through a thyroid gland with follicular carcinoma, a form of thyroid cancer. Follicular adenoma and follicular carcinoma of the thyroid gland are tumors of follicular cell differentiation that consist of a microfollicular architecture with follicles lined by cuboidal epithelial cells. A follicular adenoma is a benign encapsulated tumor of the thyroid gland. The cause of thyroid cancer is not known. It is more common in women than men. Symptoms can include swelling in the neck and difficulty swallowing or breathing. Treatment is with the surgical removal of the tumour or gland, often combined with radioactive iodine therapy. Magnification: x100 when printed at 10 centimetres wide. Human tissue.