What is Quervain's thyroiditis (subacute granulomatous thyroiditis)?

De Quervain's Thyroiditis (Subacute Granulomatous Thyroiditis)

De Quervain's thyroiditis is a self-limited, painful inflammatory disorder of the thyroid gland characterized by granulomatous changes with giant cells, typically occurring 2 weeks after a viral upper respiratory infection in genetically predisposed individuals. 1, 2

Definition and Pathophysiology

De Quervain's thyroiditis, also called subacute granulomatous thyroiditis, is an uncommon inflammatory thyroid disease that accounts for approximately 3-5% of all thyroid disorders. 1, 3 The condition is:

• Caused by viral infection in genetically susceptible individuals, though the exact etiology remains unknown 1, 2
• Characterized pathologically by granulomatous inflammation with multinucleated giant cells in thyroid tissue 1, 4
• Self-limited with complete resolution typically occurring within 6-12 months 1

Clinical Presentation

The disease presents with a distinctive clinical triad 2:

• Painful thyroid enlargement that is exquisitely tender on palpation, with pain radiating to the ear and worsening with swallowing 2, 4
• Markedly elevated erythrocyte sedimentation rate (ESR) 1, 2
• Recent history (typically 2 weeks prior) of upper respiratory viral infection 1, 2

Additional features include:

• Thyrotoxicosis present in approximately 50% of cases during the early phase 1
• Generalized somatic symptoms causing significant discomfort or prostration 5
• More common in middle-aged women 1, 3

Diagnostic Findings

Laboratory Tests

• ESR: Markedly elevated 1, 2
• C-reactive protein: Normal or slightly elevated 2
• Leukocyte count: Normal or slightly elevated 2
• Serum thyroglobulin: Usually elevated 1
• Thyroid autoantibodies: May be present 2

Imaging Studies

• Radioactive iodine uptake (RAIU): Depressed/decreased uptake on thyroid scintigraphy 1, 4
• Ultrasound: Diffuse hypoechogenic structures, though nodules may also occur 2

Cytology

Fine needle aspiration cytology shows 3, 6:

• Multinucleated giant cells
• Lymphocytes
• Loose epithelioid histiocyte groups
• Granulomas
• Isolated epithelioid histiocytes
• Colloid and neutrophil leukocytes

Important caveat: These cytomorphological features are not pathognomonic and can mimic Hashimoto's thyroiditis, granulomatous infections, sarcoidosis, and even papillary thyroid carcinoma. 3, 6

Natural History and Clinical Phases

The disease progresses through four distinct phases 2:

1. Destructive inflammation phase: Temporary hyperthyroidism due to thyroid follicle destruction
2. Euthyroid phase: Normalization of thyroid function
3. Transient hypothyroidism phase: Temporary underactive thyroid
4. Recovery phase: Return to normal thyroid function

Critical pitfall: The disease often remains unrecognized, or only the first hyperthyroid phase is diagnosed and inappropriately treated as primary hyperthyroidism. 2

Long-term Outcomes

• Complete resolution is the universal rule in the vast majority of patients 5
• Permanent hypothyroidism occurs in less than 1% of cases 5
• Recurrent disease has been reported in some patients 1
• Repeat exacerbations are uncommon but may occur in a small percentage requiring restoration of treatment 5

Differential Diagnosis

De Quervain's thyroiditis must be distinguished from 4:

• Chronic lymphocytic thyroiditis (Hashimoto's thyroiditis): Presents with hypothyroidism and goiter, confirmed by thyroid autoantibodies
• Subacute lymphocytic thyroiditis (silent thyroiditis): Autoimmune origin, commonly postpartum, with hyperthyroidism and depressed RAIU but typically painless
• Acute suppurative thyroiditis: Rare infectious disorder caused by bacteria
• Invasive fibrous thyroiditis (Riedel's thyroiditis): Presents with slowly enlarging anterior neck mass, sometimes confused with malignancy