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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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Which of the following is true about Reidel's thyroiditis
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The correct answer is  Answer- D. All the aboveA rare disorder characterized by extensive fibrosis involving the thyroid and contiguous neck structures.The presence of a hard and fixed thyroid mass clinically simulates a thyroid carcinoma.It may be associated with fibrosis in other sites in the bodn such as the retroperitoneum, and appears to be another manifestation of a systemic autoimmune IgG4-related disease, which is associated with fibrosis and tissue infiltration by plasma cells producing IgG4.