Riedel's Thyroiditis with Intense FDG Uptake Demonstrated on FDG PET/CT.

Area of Science:

• Endocrinology
• Pathology
• Nuclear Medicine

Background:

• Riedel's thyroiditis is a rare, chronic fibrosing thyroiditis characterized by extensive fibrosis.
• It can mimic malignancy, presenting diagnostic challenges.

Purpose of the Study:

• To present a case of Riedel's thyroiditis diagnosed in a 39-year-old female.
• To evaluate the role of FDG PET/CT in diagnosing and staging the condition.

Main Methods:

• Clinical presentation, biochemical tests, ultrasound, CT, and FDG PET/CT imaging were utilized.
• Core biopsy confirmed the diagnosis of chronic inflammatory process with fibrosis.

Main Results:

• The patient presented with a rapidly enlarging goiter and subclinical hypothyroidism.
• FDG PET/CT showed diffuse thyroidal uptake, with no evidence of systemic fibro-inflammatory disease.
• Biopsy confirmed Riedel's thyroiditis.

Conclusions:

• Riedel's thyroiditis can present with goiter and hypothyroidism.
• FDG PET/CT can help exclude other systemic conditions but biopsy remains crucial for diagnosis.