Proposed algorithm for management of patients with thyroid nodules/focal lesions, based on ultrasound (US) and fine-needle aspiration biopsy (FNAB); our own experience

Abstract

Background: The standard management in patients with thyroid nodules is to assess the risk of malignancy, based on cytological examination. On the other hand, there are thyroid patterns of ultrasound (US) image, associated with an increased risk of malignancy. The aim of our study was to create a diagnostic algorithm that would employ both data from US examination (expressed by a total score, according to our scoring system) and FNAB results, classified according to Bethesda system (The Bethesda System for Reporting Thyroid Cytopathology - TBSRTC categories).

Material and methods: 100 thyroid cancer foci (94 papillary carcinomas, 4 medullary carcinomas, 2 undifferentiated carcinomas) and 100 benign focal lesions were selected during postoperative histopathological examination of thyroid glands excised during surgery from 111 patients. The corresponding US images of each lesion - performed in the course of preoperative diagnostics - were evaluated for the presence of seven (7) different features in US image, suggesting a malignant character of lesion, viz. vascularity, i.e., the increased central intranodular blood flows, microcalcifications, "taller-than-wide" orientation, solid composition, hypoechogenicity, irregular margin and either absence of peripheral halo or the presence of outer shell of uneven thickness, surrounding the lesion. The sensitivity, specificity, positive predictive values, negative predictive values and odds ratios for each US feature were calculated.

Results: IN US IMAGE OF THE ANALYZED CANCER FOCI, WE OBTAINED THE FOLLOWING VALUES OF ODDS RATIO FOR EACH OF THE ABOVE MENTIONED FEATURES SUGGESTING MALIGNANCY: "taller-than-wide" orientation - odds ratio - 301.0, microcalcifications - 24.67, increased intranodular vascularity - 20.44, hypoechogenicity - 18.61, irregular margins - 7.81, absence of halo - 5.88, and solid composition - 4.16. Taking into account our own experience and the present data, in juxtaposition with the opinions of other authors, we propose a division of US features into 3 groups of different prognostic importance, expressed by a total score calculated based on our scoring system. Accordingly, microcalcifications, "taller-than-wide" orientation, the increased intranodular vascularity, and hypoechogenicity constitute one group - each of the features in this group is awarded 1 point. In turn, the characteristics of minor prognostic importance, such as irregular margin, absence of halo, solid composition, and large size (a diameter longer than 3.0 cm) - are associated with the granting 0.5 points each. The most important prognostic features - a rapid growth (enlargement) of nodules/focal lesions and a presence of pathologically altered lymph nodes are associated with the granting 3 points for each. Our scoring system can be applied in order to better assessment of thyroid US patterns in whole. In patients with a total score ranging from 0 < 4 points there is US pattern of a low risk of malignancy, with ≥ 4 < 7 points - intermediate risk, and in patients with a score ≥ 7 points - a high risk in question.

Conclusion: Complementary use of our scoring system and FNAB TBSRTC categories can help to make optimal clinical decisions as regards the selection of treatment strategy.

Figure 1

Odds ratios of analyzed US characteristics in diagnostics of malignant thyroid lesions. The values on the figure indicate the median odds ratio, with neighboring dots indicating the boundaries of 95% confidence intervals.

Figure 2

Low risk thyroid nodule/focal lesion US pattern. A. Ultrasound picture of the thyroid lesion (B-mode). The scoring system – 1.5 points (low risk US pattern 0 < 4 points); E – hypoechogenicity; C2 – solid composition; FNAB cytology in this case - category II TBSRTC; management - observation and repeat FNAB examination after 18 months. B. Ultrasound picture of the thyroid lesion (Power Doppler), peripheral blood flows.

Figure 3

Intermediate risk thyroid nodule/focal lesion US pattern. A. Ultrasound picture of the thyroid lesion (B-mode). The scoring system - 5.5 points (intermediate risk US pattern ≥ 4 < 7 points); C1 – microcalcifications; O – orientation - “taller-than-wide” shape – not shown in the figure; E – hypoechogenicity; H – the absence of “halo”; C2 – solid composition; D – diameter - below 3 cm (not shown); M – irregular margin; FNAB cytology in this case - category IV TBSRTC; management - recommend surgery. B. Ultrasound picture of the thyroid lesion (Power Doppler). The scoring system - 5.5 points (intermediate risk US pattern ≥ 4 < 7 points); V – the increased intranodular blood flows.

Figure 4

High risk thyroid nodule/focal lesion US pattern. A. Ultrasound picture of the thyroid lesion (B-mode, Power Doppler). The scoring system - 7.5 points (high risk US pattern ≥ 7 points); C1 – microcalcifications; O – orientation – shape other than “taller-than-wide” – not shown in the figure; V - the increased intranodular blood flows; E – hypoechogenicity; H – the absence of “halo”; C2 – solid composition; D – diameter - below 3 cm (not shown); M – irregular margin; FNAB cytology in this case - category V TBSRTC; management - recommend surgery. B. Ultrasound picture of the metastatic lymph node in the same case (B-mode, Power Doppler). The scoring system - 7.5 points (high risk US pattern ≥ 7 points); the increased blood flows, mainly peripheral, in the metastatic lymph node.

Figure 5

The algorithm of diagnostic and therapeutic management in thyroid nodules/focal lesions.