The Thyroid Parenchyma Is Again Mildly Heterogeneous
A 52-year-old adult female with a history of hypothyroidism, left thyroid
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A 52-year-quondam woman with a history of hypothyroidism and a left thyroid nodule presents to the endocrine dispensary for follow-up. She was initially referred 7 years prior for goiter on physical exam.
Her thyroid ultrasound revealed a heterogeneous, hypoechoic and hypervascular thyroid gland (Effigy 1) with an 8-mm hyperechoic left mid-lobe nodule (Figures 2A and 2B). Biopsy was not performed considering the nodule was less than ane cm, equally recommended by the American Thyroid Association guideline for nodules and cancer. She has been taking levothyroxine fifty mcg by oral fissure daily for the last 2 years with a normal thyroid-stimulating hormone level.
Today, she has no complaints and relates no trouble swallowing, change in neck size or change in voice. Thyroid ultrasound in the endocrine dispensary showed diffusely enlarged gland parenchyma with a heterogeneous echotexture, hyperechoic lines and increased vascular flow (Figures 1A, B). In add-on, the left nodule had increased in size to 1.4 cm × 1.1 cm × 1.2 cm and a new right nodule was identified measuring 0.ix cm × 0.8 cm × 0.5 cm. Both nodules were solid, hyperechoic compared with the rest of the hypoechoic parenchyma, with well-defined margins with scant intranodular and peripheral vascularity. A decision was made whether to biopsy the enlarging left thyroid nodule.
Ultrasound typical of Hashimoto's thyroiditis includes coarsened, heterogeneous, hypoechoic parenchyma with a micronodular blueprint and hyperechoic lines or septations suggestive of fibrosis (Figure 1A). The decreased echogenicity is a consequence of lymphocytic infiltration, whereas the hyperechoic lines are bands of fibrosis that run through the parenchyma, typical of the pathology of Hashimoto'due south thyroiditis. In addition, tiny hypoechoic micronodules measuring one mm to 7 mm are characteristic of thyroiditis with a positive predictive value for Hashimoto'due south thyroiditis of 95%. It is thought that these tiny nodules are also hypoechoic due to deposits of lymphocytes with an echogenic rim due to the fibrous strands throughout the parenchyma (Effigy 1A).
On colour Doppler, the thyroid can vary from slightly hypervascular to markedly hypervascular (Effigy 1B). Besides the diffuse form of Hashimoto's thyroiditis, discrete nodules within the diffusely abnormal parenchyma may occur. Although this is a focal thyroiditis within a sonographically normal thyroid, it is unusual and represents virtually v% of thyroid nodules. This patient had solid hyperechoic nodules in the background of the hypoechoic parenchyma of chronic thyroiditis. These nodules take the appearance of "white knight" nodules in a black background. These nodules are by and large benign with a very depression run a risk for malignancy.
Figure 1. Thyroid ultrasound. Sagittal view of the right lobe of the thyroid with typical changes of thyroiditis. A) Sagittal images showing hypoechogenicity (same color as overlaying strap muscles), heterogeneity, and hyperechoic lines. B) Diffuse vascular flow with Doppler assay.
Figures reprinted with permission from: Stephanie 50. Lee, MD, PhD
Figure 2. White knight nodules in chronic thyroiditis. White knight nodules (arrows) are solid, hyperechoic (white compared to the rest of the thyroid parenchyma) in the background of chronic thyroiditis (hypoechoic, heterogeneous and hypervascular). A) Left transverse. B) Left transverse + Doppler. C) Right transverse. D) Correct+ Doppler.
A large multicenter written report demonstrated that only 11% of nodules in glands with diffuse hypoechoic changes of chronic thyroiditis were solid and hyperechoic. Bonavita and colleagues characterized the sonographic patterns of 500 benign and malignant thyroid nodules. One of the 10 morphologic patterns was the white knight pattern described as a uniformly hyperechoic nodule in a hypoechoic background typical of Hashimoto's thyroiditis. It is critical that the hyperechoic nodule have well-defined borders, no vascularity or be isovascular with the residual of the thyroid parenchyma and no calcification. Cytology of 17 white knight nodules in the report were benign colloid nodules or Hashimoto'southward thyroiditis.
In a 2011 retrospective study of 811 nodules, researchers reported that the white knight nodules had 100% specificity for absence of malignancy. In 2010, a large multicenter written report of nodules in Hashimoto's thyroiditis also found that none of the solid and hyperechoic nodules in Hashimoto'southward thyroiditis contained cancer. These studies support the concept that it is non necessary to biopsy white knight nodules.
The 2009, revised ATA guidelines did not address this specific type of white knight nodule, merely these data are only recently published. With our patient, we discussed the very low gamble for malignancy of her thyroid nodules noted on ultrasound and recommended against biopsy in favor of watchful waiting. TSH was 1.viii mcIU/mL, and she continues to take levothyroxine 50 mcg by mouth daily. She will return in 12 months for a repeat thyroid ultrasound exam.
Stephanie Fifty. Lee, Dr., PhD, is associate professor of medicine; associate primary, section of endocrinology, diabetes and diet; and associate professor of medicine at the Boston Medical Center.
Matthew Spitzer, MD, is a young man in endocrinology, department of endocrinology, diabetes and nutrition, at Boston Medical Centre.
For more information:
- Anderson Fifty. AJR Am J Roentgenol. 2010;195:216-222.
- Bonavita JA. AJR Am J Roentgenol. 2009;193:207-213.
- Cooper DS. Thyroid. 2009;19:1167-1214.
- Virmani V. AJR Am J Roentgenol. 2011;196:891-895.
Disclosure: Drs. Spitzer and Lee report no relevant fiscal disclosures.
Source: https://www.healio.com/news/endocrinology/20120518/a-52-year-old-woman-with-a-history-of-hypothyroidism-left-thyroid
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