Tumor protrusion with intensive blood signals on ultrasonography is a strongly suggestive finding of follicular thyroid carcinoma.

Abstract

Aim: It is difficult to differentiate follicular carcinomas (FC) from follicular adenomas (FA) because ultrasonography and cytology provide very similar findings. FC is histopathologically diagnosed to have capsular and/or vascular invasion. In a few patients, tumor protrusions are observed by preoperative ultrasonography as large forms of capsular invasion of follicular carcinomas. The aim of the study was to clarify the predictive value of tumor protrusions on preoperative ultrasonography for follicular carcinomas. Material and methods: A total of 531 patients (FC: 184 patients, FA: 347 patients) undergoing thyroid surgery were included in this study. A tumor protrusion on ultrasonography was defined as follows: 1) a solid tumor extending beyond a marginal line of capsular zone of the main tumor on B-mode ultrasonography; 2) intensive blood signals observed within the protrusion area on Doppler ultrasonography. The large form of capsular invasion was defined if the protrusion lesion was histopathologically diagnosed to be a capsular invasion of follicular carcinoma. Results: The sensitivity of tumor protrusion was 0.071, specificity 0.994, positive predictive value 0.867, and negative predictive value 0.669 for FC diagnosis. For the large form of capsular invasion in FC the sensitivity of tumor protrusion was 0.813, specificity 0.982, positive predictive value 0.684, and negative predictive value 0.982. Conclusions: A tumor protrusion with intensive blood signals extending from the main tumor on ultrasonography strongly suggests a large form of capsular invasion of follicular carcinoma.

Calcifications in Thyroid Tumors on Ultrasonography: Calcification Types and Relationship with Histopathological Type

“…Calcifications of follicular carcinoma mostly presented as the following 3 types: fragmentary, massive, and egg-shell type calcifications ( Table 1(e) ). The reported ultrasonographic features in follicular carcinoma 15 18 19 20 21 22 as well as the calcification types will be helpful in diagnosing follicular carcinoma in combination with the cytopathological findings of follicular neoplasm.…”

“…That is because papillary carcinomas that present such typical features comprise the majority of thyroid malignancies. However, when we perform ultrasound examination of each patient, it is necessary to read and interpret other characteristic features such as tumor thrombus 19 , tumor protrusion 20 , or “nodule in nodule” appearance 21 to predict malignancy. Also, calcifications together with a specific ultrasound appearance such as cyst-forming 13 or diffuse swelling gland 16 should be noted for differential diagnosis in each patient.…”

Can ultrasound systems for risk stratification of thyroid nodules identify follicular carcinoma?

“…The description of individual high‐risk features differs significantly among studies, with some reporting a high prevalence of spiculated/lobulated/ill‐defined margins . Tumor protrusion has been proposed as specific criterion for FTC, even if its diagnostic performance is impaired both by protrusion‐like aspects and rarity of this kind of presentation . According to other authors, US appearance correlates with disease‐related outcomes, being less aggressive forms of FTC associated with the absence of malignant US criteria .…”

“Nodule in Nodule” on Thyroid Ultrasonography: Possibility of Follicular Carcinoma Transformed from Benign Thyroid Tumor

“…It is diagnosed as "follicular neoplasm" without a judgment of malignancy or benignancy on cytology. On the contrary, we previously reported a few cases of follicular carcinoma with a tumor thrombus [5] and tumor protrusion with intensive blood signals extending from the main tumor [6] detected by preoperative ultrasonography in combination with cytological findings of "follicular neoplasm." Therefore, ultrasonography can provide useful information on the preoperative diagnosis of follicular carcinoma in some patients.…”

“…Therefore, it is generally considered impossible to differentiate follicular carcinomas from follicular adenomas by ultrasonography. However, some characteristic ultrasound features, such as tumor thrombus [5] and tumor protrusion [6] , can provide useful information for the preoperative diagnosis of follicular carcinoma in some patients who show "follicular neoplasm" on cytology. In this report, we present 4 patients with a follicular carcinoma or neoplasm who demonstrated a "nodule in nodule" appearance on ultrasonography, which was suggested to be a follicular carcinoma or neoplasm transformed from a benign lesion located in the outer nodule.…”