Endocrine Abstracts

In patients presenting with a diffusely enlarged hard thyroid gland the differential diagnosis lies between thyroid carcinoma, lymphoma, and Riedel’s thyroiditis. We present a case of Riedel’s thyroiditis with multifocal nodular sclerosis, which improved with levothyroxine replacement.

A 40-year-old woman presented with a 3 months history of neck swelling, dysphagia and breathlessness on exertion. Examination revealed a hard, fixed, diffuse goitre. TFTs revealed fT₄ <5.2 pmol/l (9.0–24.0), TSH 62.3 mIU/l (0.20–4.0), TPO antibodies >1300 IU/l and CRP 52 μg/l. Repeat TFTs confirmed hypothyroidism and levothyroxine was commenced. Ultrasonography showed a large nodular goitre suspicious of malignancy. A CT scan revealed a large thyroid mass, encasing the oesophagus, compression of the trachea with a minimum diameter of 9 mm, infiltration of the carotid sheath, multiple bilateral pulmonary nodules, multiple suspicious lesions in the liver and enlarged para-aortic lymph nodes.

Core biopsy revealed dense fibrous tissue, with mixed chronic inflammatory cells focally infiltrating muscle and walls of veins consistent with Riedel’s thyroiditis. Immunohistochemistry revealed no epithelial cells effectively excluding paucicellular carcinoma. CT guided and thoracospic biopsy of a lung lesion revealed hyalinising granuloma. Auto-antibody screening and inflammatory markers were negative.

Four months later, symptoms improved without specific intervention other than levothyroxine. Clinical examination and imaging 6 months later revealed a significant decrease in size of the goitre, and no significant narrowing of the trachea with a minimum diameter of 12 mm. The lung nodules had significantly reduced in size.

Our patient presented with a history and imaging consistent with a diagnosis of disseminated thyroid carcinoma. Repeated attempts to obtain confirmatory histology showed only fibrous tissue. Furthermore, resolution of the inflammatory process occurred after institution of thyroxine replacement therapy. To our knowledge this is the first description of Riedel’s thyroiditis presenting with widespread nodular fibrosis, which improved following initiation of levothyroxine therapy.