Thyroid mass in patient with history of Hashimoto thyroiditis (in 40-80%)

Focal lymphomatous mass/nodule

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  Well defined, solid, hypoechoic, heterogeneous, noncalcified, solitary/multiple, unilateral/bilateral

Diffuse involvement

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  Hypoechoic, heterogeneous, rounded gland

  
  
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  Simple thyroid enlargement, minimal change in echo pattern (often missed); adjacent lymphadenopathy and background Hashimoto may be only clue

Evidence of background Hashimoto thyroiditis: Echogenic fibrous bands in lobulated, hypoechoic gland

Lymphadenopathy: Multiple ± bilateral

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  Reticulated or pseudocystic pattern, but nodes are solid with no necrosis

Color Doppler: Thyroid nodules are nonspecific: Hypovascular or chaotic intranodular vessels

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  Lymph nodes: Central > peripheral vascularity

Anaplastic thyroid carcinoma, differentiated thyroid carcinoma, metastases to thyroid, multinodular goiter

2-5% of all thyroid malignancies

Rapidly enlarging thyroid mass, frequently with associated neck adenopathy

Compression of surrounding tissues may cause dysphagia, dyspnea, or pressure symptoms

Older females, known Hashimoto thyroiditis

Pathologic diagnosis may require core needle biopsy in addition to fine-needle biopsy

Rapidly enlarging thyroid mass in elderly patient is usually due to thyroid non-Hodgkin lymphoma or anaplastic carcinoma; lack of calcification, invasion, and necrosis favors non-Hodgkin lymphoma