Histopathological Analysis of Thyroid Nodules with Taller-Than-Wide Shape in Adults.

Background: The ultrasound examination (USE) feature of taller-than-wide (TTW) shape is highly specific but low sensitive in diagnosis of thyroid carcinoma. Relationships between other USE malignant features (such as irregular margin, ill-defined, markedly hypoechoic, and microcalcification) with histopathological features have been well investigated, while studies about the histopathologic features of TTW shape are rare.

Aim: The present study aimed to investigate the histopathological features of thyroid nodules with TTW shapes.

Methods: A total of 85 thyroid nodules with TTW were selected from 1680 consecutive patients who underwent thyroid resection. USE features of the nodules, including size, location, boundary, margin, composition, echogenicity, and calcification, were recorded according to the China Thyroid Imaging Reporting and Data System (C-TIRADS). Hypoechoic lesions were further categorized as mild, moderate or markedly hypoechoic lesions. The histological features of the specimens were evaluated according to the arrangement of follicular cells, presence of papillary structures or psammoma bodies, degree of fibrosis, and amount of lymphoid infiltration. Differences in the USE and histological features between benign and malignant nodules were compared.

Results: Among the 85 nodules, 72 (84.71%) were malignant, and 13 (15.29%) were benign. Only echogenicity showed a statistically significant difference between benign and malignant nodules (P=0.003). Apart from microfoci, papillary structures, and psammoma bodies, the degree of fibrosis was also significantly different between benign and malignant tumors (all P<0.05). Regression analysis showed a trend of decreasing nodule echogenicity with increasing fibrosis frequency (odds ratio [OR] = 4.500).

Conclusion: Extensive fibrosis is the most common histopathological feature of thyroid cancer and corresponds to hypoechogenicity in USE. TTW-shaped thyroid nodules are highly suggestive of malignancy, especially those with moderate or markedly hypoechogenicity.