Giraffe pattern

Last revised by Yuranga Weerakkody on 6 Nov 2020

Giraffe pattern (also known as the pseudonodular appearance) is a distinctive ultrasound appearance characteristic of Hashimoto thyroiditis. Bonavita originally described a thyroid gland with multiple echogenic nodules, separated from one another by bands of hypoechogenicity, reminiscent of a giraffe hide 1. Studies have shown that this pattern is always benign.

The reverse pattern, multiple hypoechoic pseudonodules with ill-defined margins surrounded by echogenic areas of thyroid parenchyma or fibrosis, is also characteristic of Hashimoto thyroiditis and more similar to giraffe hide which consists of dark areas surrounded by bright lines. 

The pattern on vascular Doppler is also helpful to differentiate pseudonodules from true thyroid nodules, the hypoechoic areas are avascular and intervening parenchyma shows vascularity.

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Cases and figures

  • Figure 1: giraffe
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  • Case 1: Hashimoto thyroiditis: giraffe pattern
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