Hashimoto’s Thyroiditis 101: Thyroid Ultrasound Appearance
- US features Hashimoto’s thyroiditis.
- The US appearance is highly variable and
correlates with the progression of histopathologic changes along the course of the disease.
- The lymphoid and oncocytic cell appear homogeneous on US.
- Fibrosis elements as hyperechoic septa.
- Early in the course of the disease, the gland appears diffusely enlarged and profound hypoechoic. which correlates with lymphocytic infiltration and colloid depletion without fibrosis.
- Subclinical thyroid dysfunction is common at this stage.
- As the disease progresses, there is mild hyperechogenicity, heterogeneity, and pseudo-micronodularity (“moth-eaten·· or cotton weave) that is the result of destruction of thyroid tissue.
- Poorly outlined hypoechoic pseudonodules may be variably present, often transient. and may represent coalescent aggregates of lymphoid cell-rich tissue. which may be surrounded by echogenic septa.
- A Swiss-cheese” appearance on US. the result of small cystic lesions may be seen in the course of the disease.
- Hyperechogenic pseudonodules seen in·regenerative” nodules or as a result of aggregated fibrous tissue (“white knight “).
- “Detached” tissue nodules may be seen in chronic stages.
- Blood flow is variable: it range from absent to normal to increased on Doppler examination.
- The gland is small, atrophic, hypoechoic, and heterogeneous in end-stage disease.
- True distinct hypoechogenic thyroid nodules with or without calcifications may be seen and need USG-FNA sampling to rule out PTC or lymphoma.
- Cytologic material for confirmatory flow-cytometry studies can be easily obtained by this means.
- A “speckled” pattern is occasionally seen and probably needs a USG-FNA, because the numerous “colloid bodies” may be difficult to distinguish from the numerous psammoma bodies present in the sclerosing variant of PTC.
- Prominent lymph nodes in the central and lateral neck are almost always present.