Background

  • Acute infectious (suppurative) thyroiditis is an infection in the thyroid gland resulting in an abscess
  • Potentially life-threatening and should be treated as a medical emergency
  • Most patients with acute infectious thyroiditis are euthyroid on presentation, but some patients may have hyper- or hypothyroidism depending on the degree of destruction of the thyroid gland

Who is Most Affected

  • Most cases occur in children due to its association with pyriform sinus fistula (some cases have also been reported in children receiving chemotherapy treatment for cancer)
  • More common in patients with preexisting thyroid disease (Hashimoto thyroiditis/nodular goiter)

Incidence/Prevalence

  • Very rare (reported in about 0.1%-0.7% of patients with thyroid disease)
  • About 92% of cases are reported to occur in children
  • About 8% of cases are reported in adults (primarily with immunocompromised)

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Common Risk Factors

  • Preexisting clinical/subclinical thyroid disease
  • Congenital abnormalities (piriform sinus fistula or persistent thyroglossal duct)
  • Immunocompromised state (such patients are predisposed to unusual bacteria, such as Nocardia and Salmonella, and fungi like Candida, Coccidioides immitis, and Aspergillus)
  • Diabetes mellitus

Causes

  • Any type of infection involving the thyroid gland (other than viral)
  • Mostly caused by bacteria; most common organisms include
    • Staphylococcus (predominantly Staphylococcus aureus)
    • Streptococcus (predominantly Streptococcus pyogenes, Streptococcus epidermidis, and Streptococcus pneumoniae)
    • Escherichia coli
    • Clostridium septicum
    • Peptostreptococcus
  • Some caused by fungal infections (more common in immunocompromised), including
    • Coccidioides immitis
    • Aspergillus species
    • Actinomycosis
    • Blastomycosis
    • Candida albicans
    • Nocardia
    • Acinetobacter baumannii
    • Cryptococcus
    • Pneumocystis jiroveci
  • Rarely, may be caused by a parasitic infection (for example, Trypanosoma species)

Pathogenesis

  • Normal physiology of the thyroid gland makes it resistant to infection due to
    • High vascularity and lymphatic drainage
    • High concentration of iodine in thyroid tissue
    • Generation of hydrogen peroxide in the thyroid for synthesis of thyroid hormone
    • Encapsulation of the thyroid separating it from other structures
  • Persistent fistula in the pyriform sinus or fourth branchial arch sinus (particularly in children) can make the left thyroid lobe susceptible to infection and abscess formation

Clinical Presentation

  • Most commonly present with acute anterior neck pain (typically more severe in children)
    • May be worse when swallowing and patient may be unable to extend the neck without putting pressure on the thyroid gland
    • Often unilateral (left side)
  • Patients may also present with
    • Swollen, tender, hot neck mass (often erythematous)
    • Sign of infection (fever, local lymphadenopathy, chills), especially in children (adults may only have mild pain and no fever)
    • Compressive symptoms due to focal inflammation (dysphagia/dysphonia)
    • Necrotizing mediastinitis and pericarditis if infection spreads to the chest
  • Most patients do not present with signs or symptoms of hyper- or hypothyroidism

History

  • Ask about trauma to the neck region
  • Preexisting clinical or subclinical thyroid disease
  • Conditions associated with immunocompromised state

Physical

  • Assess for fever (more common in children than adults)
  • Evaluate for  
    • Dysphagia 
    • Pharyngitis
    • Dysphonia
  • Perform thyroid examination to assess for
    • Swelling (commonly left-sided)
    • Tenderness/warmth
    • Erythema
    • Difficulty extending the neck due to pain
  • Assess for cardiac findings associated with
    • Thyrotoxicosis – palpitations, tachycardia, widened pulse pressure
    • Hypothyroidism – bradycardia, narrowed pulse pressure

Differential Diagnosis

  • Subacute thyroiditis
    • Rare, self-limited inflammatory disease of the thyroid
    • Abnormal TSH levels, and low uptake of iodine-123 on thyroid scanning
    • Anterior neck pain – usually less severe than acute thyroiditis
  • Hashimoto thyroiditis
    • Chronic destructive autoimmune process affecting the thyroid
    • Signs/symptoms of hypothyroidism
    • Elevated thyroid peroxidase (TPO) antibody
    • Occasionally with nontender goiter
    • Rarely present with thyrotoxicosis
  • Riedel thyroiditis (Riedel struma)
    • Rare inflammatory infiltrative fibrosclerotic condition resulting in progressive destruction of thyroid tissue
    • Very firm goiter or compressive symptoms (dyspnea, stridor, dysphagia) disproportionate to the size of the thyroid
    • May be hypocalcemic due to fibrotic transformation of the parathyroid glands
    • Diagnosis is based on thyroid biopsy
  • Postpartum thyroiditis (thyroid dysfunction within 1 year of giving birth, miscarriage, or medical abortion) associated with underlying chronic thyroid autoimmune disease
  • Amyloid goiter
    • Rare condition in which amyloid deposits cause thyroid dysfunction
    • Rapidly progressing diffuse goiter that quickly leads to compressive symptoms
    • Typically euthyroid
    • Diagnosis can be made with fine needle aspiration biopsy
  • Immune reconstitution inflammatory syndrome (IRIS)
    • Lesions arise at the site of a prior infection (with immune restoration after antimicrobial therapy)
    • Symptoms similar to acute infectious thyroiditis
    • Lymphadenopathy, organomegaly, and/or fever with negative culture
    • Appears after antimicrobial therapy without evidence of new infection
  • Retropharyngeal abscess
    • Deep neck infection of the retropharyngeal space
    • Potential for airway compromise/other life-threatening complications 
    • Symptoms similar to acute infectious thyroiditis
    • Diagnosed/ruled out by CT scan
  • Drug-induced thyroiditis – related to
    • Amiodarone
    • Lithium
    • Interferon alfa
    • Interleukin-2
    • Kinase inhibitors
    • Denileukin (Ontak)
  • Radiation-induced thyroiditis
    • Thyroid pain and transient thyrotoxicosis with history of radiation exposure
  • Hemorrhage into thyroid cyst
  • Thyroid cancer

Diagnosis

  • Rapid diagnosis necessary to avoid potentially life-threatening complications
  • Suspect diagnosis in a patient (especially a child) with no history of radiation exposure or thyroid trauma who appears septic with a swollen, painful thyroid, lymphadenopathy, and fever (may not be present in adults), especially if patient:
    • Is euthyroid per thyroid function tests (TFTs)
    • Is in an immunocompromised state
    • Reports recent upper respiratory tract infection
  • Blood tests
    • TFTs (such as thyroid-stimulating hormone [TSH], thyroxine [T4], triiodothyronine [T3])
      • Most patients are euthyroid on presentation; some may present with destructive thyroiditis and thyrotoxicosis
    • Complete blood count with differential (elevated leukocytes may be seen in acute or subacute thyroiditis)
    • Thyroid autoantibodies (generally absent in acute infectious thyroiditis)
    • C-reactive protein and procalcitonin often increased
  • Imaging studies (thyroid ultrasound and CT scan) usually diagnostic
    • Findings include hypoechoic lesions in/around affected thyroid lobe, thyroid lobe destruction, and abscess formation
  • In early stages, findings may be nonspecific/difficult to distinguish from subacute thyroiditis
    • In the acute inflammatory phase, CT may show:
      • Swollen thyroid with nonspecific low-density areas
      • Displacement of trachea
      • Edema of ipsilateral hypopharynx
      • Abscess formation
  • Fine-needle aspiration biopsy with gram stain, culture, and cytopathology may be indicated when imaging shows a fluid-filled thyroid mass
    • In acute infectious thyroiditis, biopsy will show purulence, and bacteria or fungi will be detected via culturing
    • In subacute thyroiditis, biopsy will show lymphocytes, macrophages, some polymorphonuclear leukocytes, and distinctive giant cells

Management

  • Immediate management includes securing airway if compromised; perform immediate fine needle aspiration/surgical drainage of fluid to relieve pressure on trachea
  • Management involves antibiotics and surgical drainage as guided by clinical judgment
  • As the condition can be fatal if not treated urgently, patient should be hospitalized and treated with IV antibiotics
    • Start empiric parenteral antibiotics (such as nafcillin plus gentamicin or a third-generation cephalosporin) and adjust based on culture results when available
      • Continue antibiotics for 14 days or until after surgery or clinical resolution
      • For infection with Candida albicans, treat with amphotericin B and 5 fluconazole 100 mg daily 
    • If present, treat symptoms of thyrotoxicosis with beta-blockers
    • Some abscesses may require open surgical or ultrasound-guided percutaneous drainage in addition to antibiotic treatment
    • If abscess persists/progresses following drainage, consider repeat drainage and/or partial or total thyroidectomy (after acute inflammation resolves)
    • Patients with underlying pyriform sinus fistula typically require surgical removal of the fistula to avoid recurrent infections (after the period of acute inflammation)
  • Patients with particularly diffuse acute thyroiditis should have a follow-up with routine thyroid function tests to determine whether destruction has led to permanent hypothyroidism

Complications

  • Acute complications may include
    • Sepsis
    • Acute airway obstruction
  • Late complications may include
    • Transient or permanent hypothyroidism
    • Vocal cord paralysis
  • Complications of abscess extension or rupture include
    • Tracheal or esophageal perforation
    • Necrotizing mediastinitis and pericarditis
  • Patients who develop hypothyroidism, including subclinical hypothyroidism, may be at increased risk for cardiac complications

Kendra Church MS, PA-C, is a physician assistant at Dana-Farber Cancer Institute/Brigham & Women’s Hospital, and is also a senior clinical editor for DynaMed, an evidence-based, point-of-care database.

Source

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Scollard DM, Adams LB, Gillis TP, Krahenbuhl JL, Truman RW, Williams DL. The continuing challenges of leprosy. Clin Microbiol Rev. 2006;19(2):338-81. doi:10.1128/CMR.19.2.338-381.2006

Lastória JC, Abreu MA. Leprosy: a review of laboratory and therapeutic aspects–part 2. An Bras Dermatol. 2014;89(3):389-401. doi:10.1590/abd1806-4841.2014246

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Britton WJ, Lockwood DN. Leprosy. Lancet. 2004;363(9416):1209-1219. doi:10.1016/S0140-6736(04)15952-7.

Topics:

Endocrinology Infectious Disease Thyroid Disease