Riedel thyroiditis
Riedel (fibrous) thyroiditis is a rare, IgG4-related fibrosclerosing process that replaces the thyroid gland with dense fibrous tissue, producing a fixed, stony-hard, painless goiter with compressive symptoms such as dyspnea, dysphagia, and hoarseness. First-line treatment is a corticosteroid to shrink the fibrotic mass and arrest progression, with tamoxifen or rituximab reserved for refractory disease and surgery limited to airway compromise.
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What this article covers
- Overview
A rare fibrosclerosing thyroid disease: Riedel (fibrous) thyroiditis is an infiltrative process that replaces normal thyroid parenchyma and surrounding neck tissue with dense fibrous tissue…
- Epidemiology
A rare cause of thyroid disease overall: Riedel thyroiditis is uncommon relative to Hashimoto, painless, postpartum, subacute granulomatous, and acute suppurative thyroiditis.
- Risk factors
Female sex: the predominant demographic risk factor.
- Pathophysiology
Infiltrative fibrosclerosis progressively destroys the thyroid gland: dense fibrous tissue replaces normal thyroid parenchyma, in contrast to the lymphocytic infiltration of Hashimoto thyroiditis or…
- Clinical features
Fixed, firm, painless thyroid mass: the hallmark physical finding, palpably stony-hard and immobile on examination, unlike the soft-to-firm, mobile goiters of other thyroiditis subtypes.
- Differential diagnosis
Hashimoto thyroiditis: produces a diffusely enlarged, non-tender, and typically mobile goiter, unlike the stony-hard, fixed mass of Riedel thyroiditis.
- Diagnosis
The diagnosis is confirmed, once a fixed thyroid mass is identified, by open biopsy or surgical resection demonstrating fibrous tissue infiltrating the thyroid and surrounding tissue, without giant…
- Management
First, start a corticosteroid to decrease mass size and arrest progression: prednisone 40 mg PO once daily, then taper by 5-10 mg every 1-2 weeks over a total of 4-6 weeks as the mass responds, the…
- Complications
Airway obstruction: fibrotic encasement of the trachea can progress to compromise the airway, the most feared complication.
- Prognosis
Variable, depending on the extent of extracapsular fibrosis at diagnosis: more extensive compressive disease at presentation portends a more complicated course.
- Prevention
No specific primary prevention exists, since Riedel thyroiditis arises from an IgG4-related fibrosclerosing process without an identified preventable trigger.
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Related articles
- Hashimoto thyroiditis
Hashimoto thyroiditis is a chronic autoimmune process in which lymphocytic infiltration destroys the thyroid, and is the most common cause of hypothyroidism in iodine-sufficient regions such as the United States. Diagnosis rests on an elevated thyroid-stimulating hormone with a low or normal free thyroxine, and first-line treatment is lifelong levothyroxine replacement dosed to normalize thyroid-stimulating hormone.
- Subacute granulomatous thyroiditis
Subacute granulomatous (de Quervain) thyroiditis is a painful, tender destructive thyroiditis that follows a viral upper respiratory illness and produces a transient thyrotoxic phase, often followed by a hypothyroid phase, with a markedly elevated erythrocyte sedimentation rate. Treatment is symptomatic, an NSAID for mild pain or a glucocorticoid taper for moderate to severe pain, with a dramatic response within 24 to 48 hours, since thionamides and radioactive iodine have no role.
- Acute suppurative thyroiditis
Acute suppurative (infectious) thyroiditis is a rare, painful bacterial infection of the thyroid gland, typically caused by Staphylococcus or Streptococcus species in an immunocompromised host, that can progress to abscess formation. Treatment is empiric intravenous antibiotics with source-control drainage of any abscess, since the normally iodine-rich, well-vascularized, encapsulated thyroid gland resists infection and a suppurative focus rarely resolves with antibiotics alone.
- Hypothyroidism
Hypothyroidism is thyroid hormone deficiency, most commonly caused by autoimmune (Hashimoto) thyroid failure in iodine-sufficient countries, diagnosed by an elevated thyroid-stimulating hormone with a low or normal free thyroxine. First-line treatment is levothyroxine dosed at 1.6 mcg/kg lean body weight orally once daily, titrated using thyroid-stimulating hormone rechecked no sooner than 6 weeks after any dose change.