Challenging differential diagnosis, Rare disease, Educational Purpose (only if useful for a systematic review or synthesis)
Valeria Navarro-Sánchez, Luis Antonio Marín-Castañeda, Cecilia A. Gallegos, Oscar Quiroz, Miguel Ahumada-Ayala
Department of Biochemistry and Medicine, La Salle University School of Medicine, Mexico City, Mexico
Am J Case Rep 2020; 21:e928046
Available online: 2020-10-01
Riedel’s thyroiditis is a rare form of immunoglobulin G (IgG) 4-related invasive fibrosis of the thyroid gland; given its scarce incidence, standardized therapeutic guidelines are unavailable. Although complications are unusual, obstructive symptoms produced by the stony-hard goiter may put patients’ lives at risk. The diagnosis must be biopsy-proven, and treatment consists of thyroid hormone replacement and anti-inflammatory drugs, although sometimes thyroidectomy may be required.
CASE REPORT: A 69-year-old woman presented with a 7-month history of progressive hypothyroidism and obstructive dysphagia. On physical examination, she had a large, stony-hard goiter. A Doppler ultrasound study revealed a massive, avascular enlargement of the thyroid gland. A computed tomography scan failed to demonstrate any extrathyroidal extension of the abnormal tissue. A Tru-Cut biopsy of the thyroid was performed. Extensive replacement of thyroid follicles by prominent bands of fibrous tissue was observed, with follicular obliteration and mild focal occlusive phlebitis. A lymphoplasmacytic infiltrate was clearly identified; no oxyphilic nor giant cells were found. On immunohistochemistry, the immunoglobulin G (IgG) 4/IgG ratio in the plasma cell infiltrate was 40%; increased serum IgG4 levels were also found, supporting the diagnosis of Riedel’s thyroiditis. The patient was successfully treated with levothyroxine replacement and tamoxifen with prompt resolution of obstructive symptoms.
CONCLUSIONS: Fibrous thyroiditis should be considered in the differential diagnosis of primary hypothyroidism in a patient with a stony-hard goiter. Although steroids are often used as a therapeutic strategy for this disease, our patient had an excellent therapeutic response to tamoxifen, avoiding adverse effects associated with steroid therapy, the higher cost of monoclonal antibody therapy, and surgery-associated risks.
Keywords: Fibrosis, Goiter, Immunoglobulin G