Differentiation of widely invasive and minimally invasive follicular thyroid carcinoma with sonography

Abstract

Purpose: We evaluated the sonographic findings that can help differentiate widely invasive follicular thyroid carcinomas (WIFTC) from minimally invasive follicular thyroid carcinomas (MIFTC).

Methods: We retrospectively compared the sonographic and clinical findings of 24 patients (M:F=5:19) with 24 MIFTCs and 12 patients (M:F=1:11) with 13 WIFTCs that were confirmed pathologically and available in sonography at our institution between 1995 and 2007.

Results: WIFTC was more common in elderly patients than MIFTC (p<0.0001). WIFTC was seen with a larger size than MIFTC (p=0.0092). The best cut-off values for age and size were 49 years and 5.6 cm, respectively. On sonography, all tumors were seen as a well-defined oval or round mass. Heterogeneous mulberry-like echotexture was more common for WIFTC than for MIFTC (77% vs. 25%) (p=0.0046). The presence of calcifications was more frequent in WIFTC than in MIFTC (54% vs. 8%) (p=0.0041). Ring calcifications (86%) were the most common type for WIFTC. WIFTC was commonly hypoechoic (70%) and rarely cystic change (8%), but without statistical differences. When WIFTCs represented tumors with two or more findings with a statistical difference, the specificity was 96%.

Conclusion: WIFTC is distinguishable from MIFTC by sonography for patients with an age >or=49 years, a tumor >or=5.6 cm, a heterogeneous mulberry-like echotexure, or the presence of calcifications. The sonographic impression of a WIFTC can support a preoperative or intraoperative diagnosis of a difficult case as determined by FNA or with a frozen section.