Riedel’s thyroiditis is the rarest form of thyroiditis. In this condition the thyroid gland is inﬁltrated by scar tissue throughout the gland, which binds it to surrounding portions of the neck. The thyroid will feel tender and become very hard like wood. Hence, the terms ligneous (woody) or ﬁ brous (scar tissue) thyroiditis are also used to describe this peculiar condition. Because the gland attaches itself to overlying skin and deeper structures in the neck, your windpipe might feel constricted and your vocal cords could be affected as well. Your voice might become husky and swallowing could become difﬁ cult.
The diagnosis for this disorder usually involves a biopsy to rule out cancer, but the cause of the condition itself is unknown. The only treatment option is surgical removal of the front part of the gland itself. Since this condition is so rare, the portions of the thyroid that are removed during surgery must be evaluated by specialist pathologists with expertise in thyroid pathology.