Hashimoto thyroiditis, also known as lymphocytic thyroiditis or chronic autoimmune thyroiditis, is a subtype of autoimmune thyroiditis. It is one of the most common thyroid disorders.
Typically affects middle aged females (30-50 year age group with a F:M ratio of 10-15:1).
Patients usually present with hypothyroidism +/- goitre. However a very small proportion of cases (~5%) can present with hyperthyroidism (hashithyrotoxicosis). There is often a gradual painless enlargement of the thyroid gland during the initial phase with atrophy and fibrosis later on in the course.
There is autoimmunity to the thyroid gland which bears both humoral and cell mediated features. This is followed by lymphocytic infiltration of the thyroid gland with lymphoid follicles replacing thyroid follicles. This may affect the thyroid gland in either a diffuse or focal manner. Cell populations include
- lymphocytic aggregates
- transformed follicular cells (Askanazy/oxyphilic/Hurthle cells)
Later stages show added fibrosis.
- antithyroglobulin antibodies: found in ~70% of cases 2
- thyroid peroxidase antibodies (TPO): found in 90-95% of cases 2
- Turner syndrome
- primary thyroid lymphoma 6
- Hashimoto encephalopathy (rare)
- Down syndrome
- Other autoimmune disorders
It is difficult to reliably sonographically differentiate Hashimoto thyroiditis from other thyroid pathology. Ultrasound features can be variable depending of the severity and phase of disease 1,5:
- diffusely enlarged thyroid gland with a heterogeneous echotexture is a common sonographic presentation 6
- presence of hypoechoic micronodules (1-6 mm) with a surrounding echogenic septations is also considered to have a relatively high positive predictive value 3,4
- colour Doppler study usually shows normal or decreased flow, but occasionally there might be hypervascularity similar to thyroid inferno
- prominent reactive cervical nodes may be present, especially in level VI, but they have normal morphologic features
- patients are at higher risk for papillary thyroid carcinoma, so a discrete nodule should be considered for biopsy
In some situations, large nodules may be present: see nodular Hashimoto thyroiditis 10.
- early stages: may show increased uptake
- late stages: single or multiple areas of reduced uptake (cold spots).
History and etymology
It was first described in 1912 by Hikaru Hashimoto, Japanense physician (1881-1934) 7 while working in Germany in 1912.
For ultrasound appearances consider:
Ultrasound - neck and thyroid
- ultrasound (introduction)
neck and thyroid ultrasound
- Graves disease
- Hashimoto thyroiditis
- multinodular goitre
- thyroid nodules
- fine needle aspiration (FNA)
- postoperative assessment after thyroid cancer surgery
- lymph node levels of the neck
- parathyroid glands
- thyroid gland
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- 3. Yeh HC, Futterweit W, Gilbert P. Micronodulation: ultrasonographic sign of Hashimoto thyroiditis. J Ultrasound Med. 1996;15 (12): 813-9. J Ultrasound Med (abstract) - Pubmed citation
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- 6. Takashima S, Matsuzuka F, Nagareda T et-al. Thyroid nodules associated with Hashimoto thyroiditis: assessment with US. Radiology. 1992;185 (1): 125-30. Radiology (abstract) - Pubmed citation
- 7. H. Hashimoto: Zur Kenntnis der lymphomatösen Veränderung der Schilddrüse (Struma lymphomatosa). Archiv für klinische Chirurgie, Berlin, 1912, 97: 219−248.
- 8. Takashima S, Fukuda H, Tomiyama N et-al. Hashimoto thyroiditis: correlation of MR imaging signal intensity with histopathologic findings and thyroid function test results. Radiology. 1995;197 (1): 213-9. Radiology (abstract) - Pubmed citation
- 9. Vitti P, Rago T, Mazzeo S et-al. Thyroid blood flow evaluation by color-flow Doppler sonography distinguishes Graves' disease from Hashimoto's thyroiditis. J. Endocrinol. Invest. 1996;18 (11): 857-61. Pubmed citation
- 10 .Anderson L, Middleton WD, Teefey SA et-al. Hashimoto thyroiditis: Part 2, sonographic analysis of benign and malignant nodules in patients with diffuse Hashimoto thyroiditis. AJR Am J Roentgenol. 2010;195 (1): 216-22. doi:10.2214/AJR.09.3680 - Pubmed citation
- 11. Chaudhary V, Bano S. Thyroid ultrasound. Indian J Endocrinol Metab. 2013;17 (2): 219-27. doi:10.4103/2230-8210.109667 - Free text at pubmed - Pubmed citation