Which disease leads to the histological presence of lymphocyte infiltration in the thyroid?

The presence of lymphocyte infiltration in the thyroid is a hallmark of Hashimoto thyroiditis, an autoimmune disorder in which the body's immune system mistakenly attacks the thyroid gland. This infiltration is characterized by a large number of lymphocytes, which are a type of white blood cell involved in the immune response. The immune attack leads to damage and inflammation of the thyroid tissue, ultimately resulting in hypothyroidism in many affected individuals.

In Hashimoto thyroiditis, the lymphocytes not only infiltrate the thyroid parenchyma but also lead to the formation of germinal centers, which is indicative of a chronic inflammatory process. The condition is often accompanied by various thyroid autoantibodies, providing further evidence of the autoimmune nature of the disease.

While other conditions like Graves' disease also affect the thyroid, they typically feature hyperthyroidism due to different mechanisms, such as stimulating antibodies, rather than the specific lymphocytic infiltration seen in Hashimoto's. Thyroid carcinoma may present with lymphocytes in some contexts, but this is not a defining or prevalent histological feature for malignancy. Subacute thyroiditis is associated with a different type of inflammatory response, often involving neutrophils rather than predominant lymphocytic infiltration.

Hence, the association of lymphocyte infiltration