USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

What is the major risk factor for primary B-cell malignant lymphoma of the thyroid associated with Hashimoto thyroiditis?

1. Antithyroglobulin antibodies

2. HLA-Dr3 association

3. Human leukocyte antigen (HLA)-Dr5 association

4. Lymphocytic infiltrate with germinal follicles

The correct answer is: Lymphocytic infiltrate with germinal follicles

The association between Hashimoto's thyroiditis and the development of primary B-cell malignant lymphoma of the thyroid is critically linked to the presence of a lymphocytic infiltrate with germinal follicles. In Hashimoto's thyroiditis, there is a significant infiltration of thyroid tissue by lymphocytes, which can form germinal centers. These germinal centers are sites of B-cell proliferation and differentiation. The chronic inflammatory environment created by the autoimmune process in Hashimoto's thyroiditis leads to persistent antigenic stimulation of B-cells. Over time, this may result in dysregulation of normal B-cell development and potentially lead to the emergence of malignant B-cell clones, culminating in the development of lymphoma. Additionally, this pathophysiological progression aligns with the observation that patients with autoimmune thyroid diseases, especially Hashimoto's thyroiditis, have an increased risk of certain malignancies, including lymphoma. In this context, the presence of the specific immune cell infiltrate and the dynamic antigenic stimulation process play a crucial role in malignant transformation. Other options like those related to antibodies or specific HLA associations do not capture the integral relationship between the histopathological finding of lymphocytic infiltrate with germinal follicles and the oncogenic potential in this scenario. Understanding