Thyroid & parathyroid

Thyroiditis

Subacute thyroiditis



Last author update: 11 January 2022
Last staff update: 11 January 2022

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PubMed Search: Subacute thyroiditis pathology "last 5 years"[DP]

Truong Phan Xuan Nguyen, M.D.
Huy Gia Vuong, M.D., Ph.D.
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Cite this page: Nguyen TPX, Vuong HG. Subacute thyroiditis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/thyroidgranuloma.html. Accessed August 13th, 2022.
Definition / general
  • Granulomatous inflammation of the thyroid gland with characteristic clinical and microscopic findings
  • Most common cause of thyroid related neck pain and typically occurs a few weeks after a viral infection
Essential features
  • Diagnosed mainly based on clinical findings (e.g. fever, odynophagia, thyroid tenderness)
  • Histopathologically, characterized by granulomatous inflammation composed of multinucleated giant cells, foamy and epithelioid histiocytes, neutrophils, lymphocytes and plasma cells
Terminology
  • Historical name: de Quervain thyroiditis
  • Synonyms: subacute granulomatous thyroiditis, de Quervain thyroiditis, painful subacute thyroiditis, postviral thyroiditis, giant cell thyroiditis, subacute nonsuppurative thyroiditis, pseudotuberculous thyroiditis, struma granulomatosa
ICD coding
  • ICD-10: E06.1 - subacute thyroiditis
Epidemiology
Sites
Etiology
Diagrams / tables

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Thyroid function

Clinical features
Diagnosis
Laboratory
  • Thyrotoxic phase: hyperthyroid (suppressed thyroid stimulating hormone [TSH] and elevated T4 and T3) due to follicle destruction and release of hormone
  • After 4 - 8 weeks: TSH and free T4 levels may be low (Am Fam Physician 2014;90:389)
Radiology description
Radiology images

Contributed by Ayana Suzuki, C.T.

Hypoechoic nodule



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Hypoechoic nodule with poorly defined margin

High 18F-FDG uptake in enlarged right thyroid lobe

Prognostic factors
Case reports
Treatment
  • Anti-inflammatory treatment is the key
  • In some patients, no treatment is required
  • Symptoms of hyperthyroidism need to be treated with propranolol or atenolol with close follow up
  • Therapy with antithyroid drugs is not indicated because the disorder is caused by the release of preformed thyroid hormone from destroyed follicles instead of synthesis of new T3 and T4 (Am Fam Physician 2000;61:1047)
Microscopic (histologic) description
  • Inflammatory infiltrate composed of multinucleated giant cells, foamy histiocytes, epithelioid histiocytes, neutrophils, lymphocytes, plasma cells
  • Variable background of fibrosis
  • Temporal trend
    • Early stage (acute; hyperthyroidism):
      • Follicular damage and loss of epithelium and colloid
      • Neutrophils, occasional microabscesses
      • Inflammation (predominantly lymphohistiocytic), which expands into adjacent interfollicular zones
    • Mid stage (hypothyroidism):
      • Chronic inflammation: lymphocytes, plasma cells
      • Epithelioid and nonepithelioid macrophages and multinucleated giant cells adjacent to or within disrupted follicles, surround and engulf residual colloid
      • Well formed granulomata are not seen
      • Variable degrees of fibrosis
    • Late stage (resolution; recovery):
      • Fibrosis replaces destroyed follicles
      • Follicular tissue is regenerated, restoring normal structure
      • Fibrosis and inflammatory infiltrate resolves
  • Inflammatory process unevenly affects entire gland (65% bilateral) (Thompson: Diagnostic Pathology - Head and Neck, 2nd Edition, 2016)
  • Nowadays, rarely seen in resection specimens because of conservative treatment and no need for surgery (Nikiforov: Diagnostic Pathology and Molecular Genetics of the Thyroid, 3rd Edition, 2019)
Microscopic (histologic) images

Contributed by Truong Phan Xuan Nguyen, M.D.

Follicular damage

Granuloma

Multinucleated giant cells

Virtual slides

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Subacute thyroiditis

Acute (subacute) nonsuppurative thyroiditis

Cytology description
Cytology images

Contributed by Truong Phan Xuan Nguyen, M.D. and Ayana Suzuki, C.T.

Cellular smear

Multinucleated giant cells

Epithelioid cells

Giant cell

Positive stains
Sample pathology report
  • Thyroid, left lobe, fine needle aspiration:
    • Benign (Bethesda category II)
    • Subacute thyroiditis (see comment)
    • Comment: Moderately cellular aspirate with multinucleated giant cells, clustered epithelioid histiocytes, scattered lymphocytes and neutrophils consistent with subacute thyroiditis.
  • Thyroid, completion thyroidectomy:
    • Subacute thyroiditis (see comment)
    • Comment: Marked inflammation with granulomas containing multinucleated giant cells and epithelioid histiocytes without caseation necrosis. Areas of fibrosis are patchily distributed. The findings are diagnostic of subacute thyroiditis.
Differential diagnosis
  • Palpation thyroiditis:
    • Also called multifocal granulomatous thyroiditis
    • May be distributed throughout gland
    • No neutrophils
    • Multinucleated giant cells
  • Sarcoidosis:
    • Granulomas usually found in interstitium
    • Small, compact aggregates of epithelioid histiocytes
    • Giant cells may be present
    • Necrosis tends to be absent
  • Tuberculosis:
    • Granulomas with caseation
    • Granulation tissue and fibrosis
    • AFB positive
  • Chronic lymphocytic (Hashimoto) thyroiditis:
    • Diffuse, nontender thyroid gland
    • Primary features: oncocytic epithelium, lymphocytes, germinal centers
    • Lacks follicle destruction and giant cells
  • Thyroid primary and metastatic malignant tumors (BMC Endocr Disord 2019;19:86):
    • Tumors sometimes imitate symptoms of subacute thyroiditis, which may lead to delayed diagnosis of the thyroid malignancy
    • Neck sonography and thyroid FNA are helpful in identifying invasive growth and atypical malignant cells, respectively
Board review style question #1

A 40 year old woman presented to her family physician with fatigue. Several weeks ago, she had a runny nose and cough. A physical examination reveals a tender thyroid gland. Laboratory testing reveals a TSH of 0.3 mIU/L and T3 of 5 nmol/L, T4 of 4.5 nmol/L. Of the following, what would a cytologic examination of the thyroid gland reveal?

  1. Abscesses
  2. Clear nuclei and psamomma bodies
  3. Clustered epithelioid cells and giant cells
  4. Lymphocyte and oncocytic change
  5. Small follicles
Board review style answer #1
C. Clustered epithelioid cells and giant cells. This case has clinical appearances and cytologic features of subacute thyroiditis.

Comment Here

Reference: Subacute thyroiditis
Board review style question #2

A 45 year old woman reported 1 week symptoms of fatigue, fever, myalgias and neck pain. Neck examination demonstrates significant thyroid gland tenderness. Which histologic changes would likely accompany the above symptoms?

  1. Enlarged cells with large intranuclear inclusions
  2. Foreign material
  3. Granulomas with giant cells and epithelioid histiocytes
  4. Markedly atypical cells
  5. Papillae
Board review style answer #2
C. Granulomas made of giant cells and epithelioid histiocytes are a typical histologic feature of subacute thyroiditis.

Comment Here

Reference: Subacute thyroiditis
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