A 48-year-old woman has a rock-hard, painless, fixed goiter compressing the trachea. Antithyroid antibodies are negative and there is no fever. Biopsy shows dense fibrous tissue infiltrating beyond the thyroid capsule into adjacent strap muscles, with scattered lymphocytes and plasma cells. Increased production of which cytokine by these plasma cells is implicated?

• A IL-4
• B IgG4 ✓
• C IL-17
• D IgE

Explanation

Riedel thyroiditis is characterized by dense fibrosis that extends beyond the thyroid into neck structures, mimicking malignancy. It is now considered part of the IgG4-related disease spectrum, with IgG4-positive plasma cells and elevated serum IgG4 in many patients. IL-4 drives Th2 responses, IL-17 marks Th17 inflammation, and IgE reflects allergy; none defines this fibroinflammatory entity.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.