Role of Conventional Ultrasound and Color Doppler Sonography in the Diagnosis of Medullary Thyroid Carcinoma

Abstract

Early diagnosis of medullary thyroid carcinoma (MTC) can improve long-term prognosis. MTC can be detected at an early stage by calcitonin screening in all patients with thyroid nodules. This approach, however, is controversial due to high costs and a limited specificity of calcitonin. It was the aim of the present study to investigate whether ultrasonography may contribute to the diagnosis of MTC in patients with thyroid nodules. The study included 19 patients with newly diagnosed MTC. Ten patients had sporadic MTC, 7 had multiple endocrine neoplasia (MEN) type 2A, and 2 patients had MEN 2B. In all subjects conventional ultrasound, and in 14 patients color Doppler sonography were performed before primary surgery. For comparison, ultrasound appearance of 139 benign thyroid nodules was evaluated. In conventional ultrasound, MTC in 17/19 (89%) patients were hypoechoic, contained intranodular calcifications, and had no "halo sign". The combination of these criteria were found in only 8/139 (6%) of benign thyroid nodules. Intranodular blood flow was found in 11/14 patients with MTC (79%), perinodular blood flow in 7/14 MTC (50%). In conclusion, conventional ultrasound reveals a combination of hypoechogenicity, intranodular calcifications, and absence of "halo sign" in the vast majority of MTC. Since this sonographic pattern only rarely occurs in benign thyroid nodules, the results indicate that thyroid ultrasound can contribute to the diagnosis of MTC. In addition, the findings may have implications for calcitonin screening in nodular thyroid disease.

Cechy sonograficzne raków rdzeniastych tarczycy — przegląd systematyczny i metaanaliza

“…Most studies did not compare the US appearance of sporadic and hereditary MTCs. The study performed by Saller et al did not reveal significant differences, although it encompassed only ten patients with sporadic MTC, seven with MEN 2A, and two with MEN 2B [15].…”

“…According to Cai et al [14], seven of 29 examined cancers had strong intranodular flow, and 15 had moderate flow. Saller et al [15] assessed the usefulness of PD: intranodular flow was present in six of 14 examined MTCs, and intranodular flow with concomitant perinodular signal in a further five tumours. We did not find any study containing information about the appearance of MTCs in soelastography, which is believed to be an important improvement on conventional US.…”

Should we use ultrasound features associated with papillary thyroid cancer in diagnosing medullary thyroid cancer?

“…Regarding the latter, hypoechogenicity was present in all cases, and bright echogenic foci in 5/6. Saller and colleagues [5] compared 19 MTC patients referred over six years with 71 subjects with benign nodules. Seventeen (89%) MTC nodules had hypoechoic appearance, calcifications and no halo sign, with at least one US risk factor was in agreement with both these papers [8,9].…”

“…Cystic change, homogeneous echostructure, and circumscribed margins were significantly associated to MTC. Even if the above studies [4][5][6][7] represent the milestones of this topic, the design we proposed should be the correct one. By comparing both MTC and PTC with a benign control group, we recorded that MTC showed poor discrepancy with respect to the controls, while several parameters were found significantly associated with PTC when compared to benign group.…”

“…However, these large studies focused on differentiated papillary carcinoma (PTC), mainly due to its higher prevalence (about 80%) out of thyroid cancers. On the contrary, because of the low prevalence of MTC, a few papers analyzed US characteristics associated with this cancer type [4][5][6][7][8][9]. The lack of this information, together with the poor accuracy of cytology and not routine testing of calcitonin (Ct), should contribute to the low rate of MTC and, probably, to its delayed diagnosis [10,11].…”