Malignant-looking thyroid nodules with size reduction: core needle biopsy results

Abstract

Purpose: The aim of this study was to evaluate whether malignant-looking thyroid nodules with size reduction were malignant or not.

Methods: From November 2010 to July 2011, we retrospectively enrolled 16 patients with 16 nodules (11 females and five males; mean age, 55 years) who underwent core needle biopsy (CNB), and whose thyroid nodules had malignant ultrasonographic (US) features, although they showed size reduction (>20% decrease in maximum diameter) during the follow-up period (mean, 37±27 months). The histologic findings of the CNB specimen were reviewed and correlated with the US findings. US studies were analyzed for their internal content, shape, margin, echogenicity, the presence of microcalcification and macrocalcification, inner isoechoic rim, and low-echoic halo.

Results: All nodules were confirmed as benign by CNB. Pathologic analysis was available for 12 CNB specimens. US imaging showed central hypoechogenicity or marked hypoechogenicity in all cases and a peripheral isoechoic rim in 15 nodules. US-pathologic correlation showed that the central hypoechoic area was primarily composed of fibrosis (12/12) and hemorrhage (8/12) and that the isoechoic rim was composed of follicular cells.

Conclusion: In our study, the CNB results of all of the malignant-looking thyroid nodules with size reduction were benign and were primarily composed of internal fibrosis and hemorrhage. Understanding these US and pathologic features could prevent repeated fine-needle aspiration or unnecessary diagnostic surgery.

Keywords: Biopsy, fine-needle; Biopsy, large-core needle; Thyroid nodule; Ultrasonography.

Fig. 1.. A 61-year-old man with a degenerating benign nodule.

A. Transverse sonogram shows a 1.2-cm, hypoechoic solid nodule with an inner isoechoic rim (arrowhead) and a peripheral, low-echoic halo (arrows) in the left thyroid lobe. Subsequent core needle biopsy (CNB) confirmed it as degenerating nodular hyperplasia. B. A CNB specimen shows tissue consisting of a central portion of severe fibrosis and a periphery of a few follicular cells at the corresponding areas seen on sonogram (H&E, ×40).

Fig. 2.. A 63-year-old man with a degenerating benign nodule.

A. Transverse sonogram shows a 0.8-cm, markedly hypoechoic, solid nodule with an inner isoechoic rim (arrowheads) and a low-echoic halo (arrows) in the right thyroid lobe. B. A core needle biopsy specimen confirmed nodular hyperplasia with fresh hemorrhage and severe fibrosis (H&E, ×40).

Fig. 3.. Schematic, sequential feature of a degenerating nodule corresponding to Fig. 1.

A. An isoechoic nodule is surrounded by a hypoechoic rim (arrow) in the thyroid gland. B. Internal hemorrhage (Hem) compresses the remaining isoechoic solid portion of the nodule (arrows). C. Nodule is gradually contracted with degenerative changes such as fibrosis, infarction, and calcifications.