Hashimoto's thyroiditis: Ultrasonography, color doppler, and elastography evaluation with pathological correlation

Nishant Raj; Suresh Phatak; Rohan Kumar Singh; Varun Singh

doi:10.4103/jdmimsu.jdmimsu_221_22

CASE REPORT

Year : 2022 | Volume : 17 | Issue : 4 | Page : 969-971

Hashimoto's thyroiditis: Ultrasonography, color doppler, and elastography evaluation with pathological correlation

Nishant Raj, Suresh Phatak, Rohan Kumar Singh, Varun Singh
Department of Radiodiagnosis, Datta Meghe Institute of Medical Sciences, Wardha, Maharashtra, India

Date of Submission	21-May-2022
Date of Decision	04-Jul-2022
Date of Acceptance	11-Jul-2022
Date of Web Publication	10-Feb-2023

Correspondence Address:
Dr. Suresh Phatak
Department of Radiodiagnosis, Datta Meghe Institute of Medical Sciences, Sawangi (Meghe), Wardha - 442 001, Maharashtra
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jdmimsu.jdmimsu_221_22

Abstract

Thyroiditis is a general term for several inflammatory thyroid disorders ranging from autoimmune, infective, and drug induced to ionizing radiation. Ultrasound is the imaging modality of choice in the evaluation of thyroid-related pathologies. B-mode and color Doppler provide for a noninvasive and sensitive method in the evaluation of thyroiditis. Elastography is a recent modality of ultrasound. It helps in differentiating benign from malignant diseases. A definite diagnosis is often not possible on ultrasound alone, correlation of ultrasonography findings with elastography and clinical and biochemical parameters help us reach an appropriate diagnosis in most of the cases and further imaging is seldom warranted.

Keywords: Color Doppler, elastography, thyroiditis, ultrasound

How to cite this article:
Raj N, Phatak S, Singh RK, Singh V. Hashimoto's thyroiditis: Ultrasonography, color doppler, and elastography evaluation with pathological correlation. J Datta Meghe Inst Med Sci Univ 2022;17:969-71

How to cite this URL:
Raj N, Phatak S, Singh RK, Singh V. Hashimoto's thyroiditis: Ultrasonography, color doppler, and elastography evaluation with pathological correlation. J Datta Meghe Inst Med Sci Univ [serial online] 2022 [cited 2023 Mar 28];17:969-71. Available from: http://www.journaldmims.com/text.asp?2022/17/4/969/369486

Introduction

Term thyroiditis refers to inflammation of the thyroid gland which can be acute, subacute, or autoimmune. Various forms of thyroiditis have been described; some of the common ones are Hashimoto's thyroiditis, Graves' thyroiditis, Reidel's thyroiditis, acute infectious thyroiditis, and subacute granulomatous thyroiditis. Named after Dr. Hakaru Hashimoto who first described the disease, Hashimoto's thyroiditis or chronic lymphocytic thyroiditis is the most common autoimmune cause and is the most common cause of hypothyroidism.^[1] It tends to affect women more than men, most commonly seen in young or middle-aged women, typically between 30 and 50 years. Furthermore, there is an association with other autoimmune diseases such as Graves' disease, lupus, and pernicious anemia. The thyroid function in these patients is either normal or has mild hypothyroid status. Clinically, the patients usually present with painless swelling in the neck region which on examination is firm to palpation, irregular, and mildly enlarged. The presence of antithyroid peroxidase and/or antithyroglobulin antibodies is a hallmark feature of Hashimoto's disease. The disease is often seen in genetically susceptible patients, who when exposed to certain environmental triggers tend to manifest the disease. According to available literature, pregnancy appears to be one of the most important of such triggers.^[2] Cytotoxic T-cells along with T-helper cells are involved in the direct destruction of the gland which leads to the state of hypothyroidism. Histologically, there is either a focal or diffuse infiltration of lymphocytes in the thyroid gland with intervening areas of fibrosis and germinal centers.^[3] There are two recognized forms of Hashimoto's thyroiditis – nodular focal form and diffuse form both of which have different ultrasonography appearances.^[4]

Case Report

A 27-year-old female presented with slow-growing nonpainful swelling in the neck region for the past 3 years, the patient gave a history of increased sleep, generalized fatigue, and irregular menstrual cycles. On local examination, there was generalized swelling of the thyroid gland with was firm to palpation and nontender. There was no history of recent viral or upper respiratory tract infection, dysphagia, dyspnea, or hoarseness of voice. The patient was not on any medications and there was no significant past medical/surgical/obstetric history. Laboratory examination revealed elevated thyroid-stimulating hormone and low T3 and T4 suggestive of hypothyroid status. On ultrasound examination [Figure 1], both the thyroid lobes and isthmus were enlarged, there were multiple ill-defined hypoechoic nodules with intervening normal parenchyma and linear fibrous septa giving heterogeneous coarse echotexture. On Doppler ultrasound [Figure 2], there was diffuse hypervascularity across both lobes. Multiple centimetric pre- and paratracheal reactive lymph nodes were seen [Figure 3]. Elastography revealed a type 2 pattern with a strain ratio of 1.25 suggestive of benign lesion. Fine-needle aspiration cytology revealed findings consistent with Hashimoto's thyroiditis.

Figure 1: USG and strain elastography of thyroid showing enlarged gland with multiple ill-defined nodules and echogenic strands within, elastography pattern was type 2 with strain ratio of 1.25 indicating a benign etiology. USG: Ultrasonography

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Figure 2: Diffuse hypervascularity seen in enlarged thyroid gland on color Doppler

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Figure 3: USG of the neck showing pre- and paratracheal lymphadenopathy. USG: Ultrasonography

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Discussion

Normally on ultrasound, the thyroid gland appears homogenously echogenic and has a uniform echotexture. In terms of dimensions, the lobes are usually 4–6 cm craniocaudally and 1.3–1.8 in anteroposterior dimension taken in the transverse plane. The isthmus can have an anteroposterior thickness of up to 3 mm.^[5] Coming to Imaging of different types of thyroiditis on sonography, In Hashimoto's disease, there are two forms, focal nodular form and diffuse form. The most common appearance is that of a thyroid gland that is diffusely enlarged having a heterogeneous echotexture with the presence of few hypoechoic nodules (1–6 mm) and surrounding fibrous septations giving rise to a “Giraffe pattern.” Following continuous inflammation, the gland becomes diffusely enlarged, hypoechoic, and studded with multiple hypoechoic pseudonodules that are separated by fibrous septa. Often, there are surrounding reactive lymph nodes with normal morphology, most commonly seen in the level VI region. On color Doppler, there is usually a diffuse increase in vascularity, although there may be normal or even decreased vascularity in long-standing cases wherein the thyroid itself may become atrophic.^[6] In the focal nodular form, the usual presentation is that of a hypoechoic nodule which has an ill-defined border and is relatively small in size, this appearance sometimes tends to look like a malignant thyroid nodule hindering the diagnosis. Color Doppler findings in these nodules are not specific to Hashimoto's thyroiditis. In the latter stages of Hashimoto's thyroiditis, the thyroid gland becomes atrophic, has ill-defined margins, and echotexture is heterogeneous with more fibrotic changes. Regarding color Doppler, the findings tend to vary according to the time of presentation, early on there is usually diffuse hypervascularity which tends to decrease as the disease progresses and in the later stages, there is often a picture of diffuse hypovascularization owing to fibrous changes.^[4]

Important to keep in mind is the fact that these patients are at an increased risk of developing thyroid lymphoma and papillary carcinoma. In terms of thyroid lymphoma, there is an 80-fold higher risk when compared to the general population. A sudden increase in the size of the thyroid gland in a patient of Hashimoto's thyroiditis should be considered thyroid lymphoma unless proven otherwise. On ultrasound, thyroid lymphoma appears as a lobulated, discrete, and hypoechoic mass with intervening hyperechoic septa.^[2]

Elastography is a noninvasive dynamic technique which uses ultrasound to detect tissue stiffness by measuring the amount of distortion when an external force is applied. The main application of elastography in thyroid pathology is for the characterization of thyroid nodules and to distinguish benign from malignant lesions. There are two elastography methods, i.e., strain elastography and shear-wave elastography, here, in our center, we used the strain elastography method. In strain elastography, the external force is applied with the probe which causes deformation in the adjacent tissue. Stiffer tissue moves less compared to more elastic tissue. The elastography images are then superimposed over the conventional grayscale image and displayed as a color map.^[7] Thereafter using Qualitative ultrasound elastography (USE) scoring system based on USE scale of Itoh et al. four different patterns are distinguished. Elastography scoring based on USE scale of Itoh et al:^[8]

Score 1: Low stiffness over all nodules: entirely green
Score 2: Low stiffness over the majority of nodules: Mostly green with few blue areas
Score 3: High stiffness over the majority of nodules: Mostly blue with few green areas
Score 4: High stiffness over all nodules: entirely blue.

The thyroid lesions having a score of 1 and 2 are considered benign, whereas those having scores of 3 and 4 are considered suspicious for malignancy. We can also perform semiquantitative assessment by comparing the tissue strain in the pathological part with normal glandular parenchyma; this gives us a strain ratio. A higher strain ratio is associated with malignant conditions.^[9]

To conclude, ultrasound imaging along with color and power Doppler appears to be the imaging modality of choice in the evaluation of the majority of inflammatory conditions of thyroid with elastography providing additional complementary information as to whether the lesion is benign or malignant, helping in early diagnosis and better patient management.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Pearce EN, Farwell AP, Braverman LE. Thyroiditis. N Engl J Med 2003;348:2646-55.
2.	Daniels GH, Li JH, Barbesino G. Imaging “Thyroiditis”: A primer for radiologists. Curr Probl Diagn Radiol 2021;50:937-45.
3.	Amani HK. Histopathologic and immunohistochemical features of Hashimoto thyroiditis. Indian J Pathol Microbiol 2011;54:464-71. [PUBMED] [Full text]
4.	Takahashi MS, Moraes PH, Chammas MC. Ultrasound evaluation of thyroiditis: A review. J Otolaryngol Rhinol 2019;2:127.
5.	Nachiappan AC, Metwalli ZA, Hailey BS, Patel RA, Ostrowski ML, Wynne DM. The thyroid: Review of imaging features and biopsy techniques with radiologic-pathologic correlation. Radiographics 2014;34:276-93.
6.	Takashima S, Matsuzuka F, Nagareda T, Tomiyama N, Kozuka T. Thyroid nodules associated with Hashimoto thyroiditis: Assessment with US. Radiology 1992;185:125-30.
7.	Stoian D, Bogdan T, Craina M, Craciunescu M, Timar R, Schiller A. Elastography: A new ultrasound technique in nodular thyroid pathology. In: Thyroid Cancer – Advances in Diagnosis and Therapy. IntechOpen: 2016.
8.	Itoh A, Ueno E, Tohno E, Kamma H, Takahashi H, Shiina T, et al. Breast disease: Clinical application of US elastography for diagnosis. Radiology 2006;239:341-50.
9.	Phatak S, Jain S, Madurwar K, Daga S, Jain S, Gupta R. Evaluation of role of sonoelastography in solitary thyroid nodule with pathological correlation. J Datta Meghe Inst Med Sci Univ 2020;15:372. [Full text]