Thyroid Ultrasound > Top 10 Pathology > 3. Papillary Carcinoma

Papillary Carcinoma

Papillary cancer is the most common thyroid malignancy, accounting for 75% to 80% of thyroid cancers, with excellent prognosis. Approximately 15% of thyroid carcinomas behave in an aggressive manner, however. Risk factors for aggressive behavior of papillary microcarcinomas (papillary cancers less than 10 mm in size) include extracapsular invasion, metastatic lymph node size, hoarseness, and postoperative thyroglobulin levels.

The most specific sonographic finding of papillary cancer is the presence of punctuate, non-shadowing echogenic foci termed microcalcifications (see below image from Ultrasound Clinics Apr 2009), which are believed to represent dystrophic calcifications associated with psammoma bodies. Although this finding has a high specificity (85%95%) sensitivity is only 25% to 59%. Most papillary cancers are solid (87%) and hypoechoic (86%) compared with the surrounding thyroid parenchyma (see below image from Ultrasound Clinics Apr 2009). Some evidence of intrinsic vascularity is generally seen, though the distribution of vascularity has not been found to be a reliable finding. Papillary thyroid cancer metastasizes by way of lymphatics to cervical lymph nodes, which may contain microcalcifications, internal vascularity, and cystic change because of extensive degeneration.

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