A 48-year-old woman presents with a rock-hard, fixed anterior neck mass causing compressive dysphagia. Intraoperatively the surgeon notes dense fibrous tissue extending into adjacent strap muscles, making dissection difficult. Biopsy shows keloid-like fibrosis replacing thyroid parenchyma with sparse inflammation rich in IgG4-positive plasma cells. Which condition is this entity most closely allied to?
- A Anaplastic thyroid carcinoma
- B IgG4-related disease spectrum ✓
- C Subacute lymphocytic thyroiditis
- D Follicular thyroid carcinoma with extensive invasion
Correct answer: B. IgG4-related disease spectrum
Explanation
Riedel thyroiditis produces a stony-hard, fixed goiter with fibrous extension beyond the capsule into neck structures, and it is now considered part of the IgG4-related disease family. Its main clinical importance is mimicking anaplastic carcinoma and causing compression symptoms. The key discriminator from anaplastic carcinoma is the absence of malignant epithelial cells within the fibrous tissue on adequate biopsy.
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.