Endocrine Abstracts

Introduction: According to the results of several studies and meta-analyses, certain ultrasound features are associated with increased risk of thyroid malignancy. However, most of those research papers included mainly papillary thyroid cancers (PTCs); these results cannot be simply extrapolated for the differentiation of follicular thyroid adenomas and cancers (FTAs and FTCs). The aim of the present study was to perform a meta-analysis of so far conducted research and identify sonographic features suggesting malignancy in case of follicular lesions, potentially differentiating FTA and FTC.

Material and Methods: We carried out a meta-analysis following the Cochrane and PRISMA guidelines. We searched PubMed, MEDLINE, Academic Search Complete, CINAHL Complete, CINAHL, Scopus, Cochrane, Health Source: Nursing/Academic Edition, Web of Knowledge, MasterFILE Premier, Health Source – Consumer Edition, Agricola, Dentistry and Oral Science Source databases from January 2006 up to July 2018 to find all relevant, full-text journal articles written in English. The search strategy included Medical Subject Headings terms and keywords: ‘thyroid and (‘follicular cancer’ or ‘follicular carcinoma’ or ‘follicular neoplasm’ or ‘follicular adenoma’ or ‘follicular nodule’) and (ultrasound or ultrasonography or elastography or ‘color doppler’ or ‘power doppler’)’. The pooled estimates of sensitivity, specificity, positive and negative predictive value (PPV, NPV), and odds ratios were obtained from the bivariate model.

Results: After a complete systematic review was performed, 15 studies met the inclusion criteria. They covered analyses of 15209 nodules. The overall odds ratios for particular features giving a FTC risk varied from 1.44 to 10.19. Specificity to predict FTC for individual features varied from 18 to 100%, and the sensitivity ranged from 1 to 94%. NPV was 64–92%, and PPV was 28–96%. The highest overall odds ratio in increasing the risk of malignancy was calculated for tumor protrusion (OR = 10.19; 95% CI : 2.62–39.71), microcalcifictions or mixed type of calcifications (micro- and macrocalcifications): 6.10 (3.00–12.50), irregular shape: 5.89 (1.09–31.82), solid or mainly solid structure: 5.22 (1.70–16.05) and marked hypoechogenicity: 4.25 (2.57–7.05). The lowest OR was characteristic for doppler pattern 3 or more: 1.44 (0.76–2.74). The probability of FTA diagnosis suggests the oval or round shape of the lesion, presence of cystic component. Less specific features suggesting benignity are lack of calcifications and visible halo.

Conclusions: The sonographic features associated with malignancy of follicular lesions are distinct from those widely reported for all thyroid cancers, including PTC, and may be a useful tool to guide thyroid nodules management.