Atypical Presentation of Riedel's Thyroiditis: Multifocal Nodular Fibrosis and Resolution with Levothyroxine.

BACKGROUND Riedel's thyroiditis is characterised by chronic inflammatory invasive fibrosclerosis of the thyroid gland, surrounding structures, and extrathyroidal fibrosis. We present a case of Riedel's thyroiditis associated with nodular fibrosis of the lungs and liver. CASE A 40-year-old woman presented with a 3-month history of neck swelling, difficulty swallowing and breathlessness on exertion. Core biopsy of the goitre revealed dense fibrous tissue with mixed chronic inflammatory cells. A staging computed tomography scan revealed a large thyroid mass encasing the oesophagus and compressing the trachea, multiple bilateral pulmonary nodules with no evidence of lymphadenopathy, and multiple suspicious nodular lesions in the liver. A thorascopic biopsy of a lung lesion in its entirety revealed a hyalinising lung lesion with no evidence of malignancy. Following the introduction of levothyroxine replacement, symptomatic improvement occurred in parallel with improvements in imaging. CONCLUSION To our knowledge, this is the first description of Riedel's thyroiditis presenting with nodular extrathyroidal fibrosis, and which showed resolution following institution of levothyroxine.