Sonographic and Clinical Features of Papillary Thyroid Microcarcinoma Less than or Equal to Five Millimeters: A Retrospective Study

<div><p>Objective</p><p>To retrospectively compare the sonographic and clinical features of papillary thyroid microcarcinoma (PTMC) ≤5 mm and PTMC >5 mm to improve the diagnostic value of ultrasonography.</p><p>Methods</p><p>A total of 367 cases of PTMC between January 2013 and December 2014 was included in this study. The patients were classified into group A (≤5 mm, n = 181) or group B (>5 mm, n = 186), and the sonographic and clinical features were reviewed and compared between the two groups.</p><p>Results</p><p>There was no significant difference in the shape, ratio of length/width, boundary, peripheral halo ring, echogenicity, cystic change and accompanying Hashimoto's thyroiditis between these two groups. However, the calcification (61.3% vs. 72.6%) and hypervascularity (13.8% vs. 24.7%) were more frequent in group B (p = 0.026 and 0.008, respectively). The patients were younger, and more patients were aged less than 45 years (41.4% vs. 57.0%) in group B. Capsular invasion (7.2% vs. 34.4%), multifocality (21.5% vs. 48.9%), bilaterality (17.1% vs. 39.8%), central lymph node metastasis (13.8% vs. 38.2%) and lateral lymph node metastasis (1.1% vs. 5.4%) were more frequent in group B. No clinical or sonographic feature was related to cervical lymph node metastasis in group A, while less than 45 years in age (p = 0.010), male gender (p = 0.040), capsular invasion (p<0.001), multifocality (p = 0.016) and calcification (p = 0.042) were related to cervical lymph node metastasis in group B.</p><p>Conclusions</p><p>The sonographic features of PTMC ≤5 mm were similar to those of PTMC >5 mm, including an irregular shape, a length/width ratio of ≥1, an unclear boundary, no peripheral halo ring, hypoechogenicity, no cystic change, calcification, no hypervascularity and no accompanying Hashimoto's thyroiditis. The clinical features of PTMC ≤5 mm were less aggressive than those of PTMC >5 mm.</p></div

Comparison of clinical features between the two groups.

<p>Comparison of clinical features between the two groups.</p

Comparison of sonographic features between the two groups.

<p>Comparison of sonographic features between the two groups.</p

Clinical features related to lymph node metastasis in group B.

<p>Clinical features related to lymph node metastasis in group B.</p

A 38-year-old female patient with papillary thyroid microcarcinoma less than or equal to 5 mm.

<p>(a) The longitudinal gray scale sonogram shows an irregular shape, a length/width ratio of ≥1, an unclear boundary, no peripheral halo ring, hypoechogenicity, no cystic change and no accompanying Hashimoto's thyroiditis. (b) The longitudinal color sonogram shows no hypervascularity. (c) The transverse gray scale sonogram shows an irregular shape, a length/width ratio of ≥1, an unclear boundary, no peripheral halo ring, hypoechogenicity, no cystic change and no accompanying Hashimoto's thyroiditis. (d) The transverse color sonogram shows no hypervascularity.</p

Sonographic features related to lymph node metastasis in group A.

<p>Sonographic features related to lymph node metastasis in group A.</p