Introduction
Background
The broad category of thyroiditis includes the following inflammatory diseases of the thyroid gland: (1) acute suppurative thyroiditis, which is due to bacterial infection; (2) subacute thyroiditis, which results from a viral infection of the gland; and (3) chronic thyroiditis, which is usually autoimmune in nature. In childhood, chronic thyroiditis is the most common of these 3 types. The second form of thyroiditis, Riedel struma, is rare in children. Secondary thyroiditis may be due to the administration of amiodarone to treat cardiac arrhythmias or the administration of interferon-alpha to treat viral diseases.
Three multinuclear, giant cell granulomas observed in a fine-needle aspiration biopsy of the thyroid; from a patient with thyrotoxicosis from lymphocytic or subacute granulomatous thyroiditis.
Pathophysiology
Acute suppurative thyroiditis is rare in childhood because the thyroid is remarkably resistant to hematogenously spread infection. Most cases of acute thyroiditis involve the left lobe of the thyroid and are associated with a developmental abnormality of thyroid migration and the persistence of a pyriform sinus from the pharynx to the thyroid capsule. The usual organisms responsible include Staphylococcus aureus, Streptococcus hemolyticus, and pneumococcus. Other aerobic or anaerobic bacteria may also be involved.
Subacute thyroiditis is generally thought to be due to viral processes and usually follows a prodromal viral illness. Various viral illnesses may precede the disease, including mumps, measles, influenza, infectious mononucleosis, adenoviral or Coxsackievirus infections, myocarditis, or the common cold. Other illnesses or situations associated with subacute thyroiditis include catscratch fever, sarcoidosis, Q fever, malaria, emotional crisis, or dental work. The disease is more common in individuals with human leukocyte antigen (HLA)–Bw35.
Because chronic thyroiditis in children is usually due to an autoimmune process, it is HLA-associated, similar to other autoimmune endocrine diseases. The specific alleles in the atrophic and goitrous forms of the disease vary. The histologic disease picture varies, but lymphocytic thyroid infiltration is the hallmark of the disease and frequently obliterates much of the normal thyroid tissue. Follicular thyroid cells may be small or hyperplastic. The degree of fibrosis among patients also widely varies. Children usually have hyperplasia with minimal fibrosis. The blood contains autoantibodies to thyroid peroxidase and, frequently, autoantibodies to thyroglobulin. Autoimmune thyroiditis is also frequently part of the polyglandular autoimmune syndromes.
Frequency
United States
Studies in the United States and Western Europe report a prevalence of 1.2% in individuals aged 11-18 years. Approximately 25% of adults with type 1 diabetes have thyroiditis, about one half of whom have hypothyroidism. Approximately 10% of children with type 1 diabetes have antithyroid antibodies. Thirteen of 121 children with vitiligo were also found to have subsequent evidence of autoimmune thyroiditis.1 The disease is also more common in children with Down syndrome or Turner syndrome. Acute suppurative thyroiditis is rare in Western nations. Subacute thyroiditis is rare in childhood.
International
The prevalence of chronic autoimmune thyroiditis varies depending on screening procedures. A Greek study showed a prevalence of thyroid antibodies as high as 12.5% in some areas. Few data are available regarding the incidence of the various forms of thyroiditis in the non-Western world. Acute thyroiditis is more common in geographic areas where antibiotic use is less prevalent.
Mortality/Morbidity
Long-term morbidity or mortality from thyroiditis is uncommon. Patients with autoimmune thyroiditis frequently develop hypothyroidism and require lifelong treatment. Patients with subacute thyroiditis may briefly have hyperthyroidism but usually regain normal thyroid function. Patients with acute thyroiditis generally maintain normal thyroid function.
Sex
The pediatric male-to-female ratio for autoimmune thyroiditis ranges from 1:2 to 1:6. This is low when compared with the 90% female predominance in adults.2,3,4
Clinical
History
- Acute thyroiditis
- A history of acute illness, including fever, chills, neck pain, sore throat, hoarseness, and dysphagia, is common.
- Neck pain is frequently unilateral and radiates to the mandible, ears, or occiput. Neck flexion reduces the severity of the pain. The pain worsens with neck hyperextension.
- Subacute thyroiditis
- Neck tenderness and swelling may occur.
- Occasionally, the initial symptoms are those of hyperthyroidism.
- Systemic symptoms such as weakness, fatigue, malaise, and fever are usually low grade.
- Chronic autoimmune thyroiditis is observed in the following 3 patterns:
- Goiter that is usually diffuse and nontender: Systemic illness is not evident. The thyroid gland is frequently 2-3 times its normal size and may be larger. The patient, parent, or physician may discover the goiter.
- Symptoms of hypothyroidism: In children, this frequently includes poor growth or short stature. Adolescent girls may have primary or secondary amenorrhea. Boys may have delayed puberty. Because the disease develops slowly, the patient or parent may not notice other signs of hypothyroidism, including constipation, lethargy, and cold intolerance. The child with diabetes may have decreasing insulin requirement.
- Symptoms of hyperthyroidism: These may include poor attention span, hyperactivity, restlessness, heat intolerance, or loose stools.
- Asymptomatic thyroiditis with or without thyroid function abnormalities may also be discovered upon routine screening of children at high risk; these include children with Down syndrome or Turner syndrome and children with other autoimmune endocrine disorders (eg, type 1 diabetes, Addison disease, vitiligo).
Physical
- Acute thyroiditis
- The patient may have a fever of 38-40°C.
- Acute illness may be evident.
- Neck tenderness is present, and the swollen thyroid gland is tender. The swelling and tenderness may be unilateral. Erythemas develop over the gland, and regional lymphadenopathy may develop as the disease progresses. Abscess formation may occur.
- Subacute thyroiditis
- The patient may have signs of systemic illness, such as low-grade fever and weakness.
- Signs of hyperthyroidism, including increased pulse rate, widened pulse pressure, fidgeting, tremor, nervousness, tongue fasciculations, brisk reflexes (possibly with clonus), weight loss, and warm moist skin, may be present.
- The thyroid gland may be enlarged and tender, with tenderness exacerbated by neck extension.
- Chronic autoimmune thyroiditis
- Initially, an enlarged, lumpy, bumpy, and nontender thyroid is often present. The gland may not be enlarged, particularly in children who have profound hypothyroidism. Signs of hypothyroidism include slow growth rate, weight gain, slow pulse, cold dry skin, coarse hair and facial features, edema, and delayed relaxation of the deep tendon reflexes.
- Signs of hyperthyroidism are occasionally present early in the disease.
Causes
- Acute suppurative thyroiditis is more common in poorer geographic areas where antibiotic use is less prevalent. It usually occurs in children with embryologic abnormalities such as a persistent thyroglossal duct or brachial cleft cysts.
- Chronic autoimmune thyroiditis is more common in developed countries with increased iodine intake.
- Children with Down syndrome or Turner syndrome and those who have type 1 diabetes or another autoimmune endocrine disease are at particular risk of chronic thyroiditis.
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| References |
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Further Reading
Keywords
thyroiditis, acute thyroiditis, autoimmune thyroiditis, chronic lymphocytic thyroiditis, Hashimoto thyroiditis, subacute thyroiditis, thyroadenitis, acute suppurative thyroiditis, chronic thyroiditis, Riedel struma, Riedel thyroiditis, atrophic thyroiditis, goitrous thyroiditis, vitiligo, hypothyroidism, persistent thyroglossal duct, brachial cleft cysts, Down syndrome, Down’s syndrome, Turner syndrome, Turner’s syndrome, type 1 diabetes, Staphylococcus aureus, Streptococcus hemolyticus, pneumococcus, mumps, measles, influenza, infectious mononucleosis, Coxsackievirus infections, myocarditis, common cold, catscratch fever, sarcoidosis, Q fever, malaria, treatment, diagnosis
