Which condition is associated with rapid enlargement of the thyroid gland in patients with Hashimoto's thyroiditis?

Rapid enlargement of the thyroid gland in patients with Hashimoto's thyroiditis is most commonly associated with thyroid lymphoma. Hashimoto's thyroiditis is an autoimmune condition that often leads to hypothyroidism and can cause chronic inflammation of the thyroid. Over time, this inflammation can create an environment that predisposes the thyroid tissue to malignant transformation.

Thyroid lymphoma, particularly non-Hodgkin's lymphoma, can manifest as a sudden increase in the size of the thyroid gland, distinguishing it from the gradual enlargement that typically characterizes goiter or the enlargement associated with other thyroid conditions. This rapid enlargement in thyroid lymphoma may be due to the proliferation of lymphoid tissue in the thyroid, which can occur in the setting of chronic inflammation, such as that seen in Hashimoto's thyroiditis.

In contrast to thyroid lymphoma, a thyroid adenoma typically results in a solitary, often benign tumor, and would not usually be associated with rapid enlargement. Subacute thyroiditis usually presents with a painful, tender thyroid and often resolves on its own without causing significant ongoing enlargement of the gland. A goiter is a general term for any enlargement of the thyroid, often occurring gradually and not rapidly as seen with thyroid lymphoma. Thus, the context of Hashimoto's thyroid