Both TI-RADS and the ATA guidelines have high sensitivity and NPV for the diagnosis of thyroid carcinoma. These systems are feasible for clinical application, allowing to better select patients to undergo fine-needle aspiration biopsies.

Objective Prospective data on the accuracy of ultrasound (US) classification systems in thyroid nodules are still scarce. The aim of this study is to compare the accuracy of the American College of Radiology Thyroid Imaging Reporting and Data System (ACR‐TIRADS) and European (EU)‐TIRADS classification systems. Design and Patients Consecutive patients with one or more thyroid nodule(s) who underwent fine‐needle aspiration (FNA) under ultrasonographic guidance (FNA‐US) were prospectively evaluated. Measurements Clinical evaluation and US data were collected. The reference standard used for this study was FNA‐US cytology and histopathological diagnosis. Results A total of 186 thyroid nodules in 166 patients were evaluated, resulting in 168 nodules from 149 patients with conclusive benign or malignant results. Sensitivity, specificity, negative predictive value (NPV) and false negative (FN) were 100.0%, 28.7%, 100.0% and 0.0%, respectively, for ACR‐TIRADS; and 90.0%, 19.1%, 96.8% and 9.1% (n = 1), respectively, for EU‐TIRADS. The number of unnecessary FNA‐US indicated by ACR‐TIRADS was lower than EU‐TIRADS (71.3% vs. 80.9%, p = .017), and the number of possibly avoided FNA‐US was higher (26.7% vs. 17.8%). Using the same threshold of ACR‐TIRADS to indicate FNA‐US in EU‐TIRADS 3 nodules (2.5 cm), there was an improvement in specificity (30.6%) and avoided FNA‐US (28.6%). The best performance of both systems was demonstrated when FNA‐US would be indicated only in highly suspicious nodules and/or in the presence of lymphadenopathy, with 85.7% and 89.3% of possibly avoided FNA‐US for ACR‐TIRADS and EU‐TIRADS, respectively, without increasing FN. Conclusion Both systems presented high sensitivity, but low specificity in selecting nodules for FNA‐US. The use of nodular size for FNA‐US selection is questioned.

Even though it is a rare event, most associations of thyroid carcinoma with subacute thyroiditis described in the literature are related to its granulomatous form (Quervain's thyroiditis). We present a patient with subacute lymphocytic thyroiditis (painless thyroiditis) and papillary thyroid cancer that was first suspected in an initial ultrasound evaluation. A 30-year old female patient who was referred to the emergency room due to hyperthyroidism symptoms was diagnosed with painless thyroiditis established by physical examination and laboratory findings. With the presence of a palpable painless thyroid nodule an ultrasound was prescribed and the images revealed a suspicious thyroid nodule, microcalcification focus in the heterogeneous thyroid parenquima and cervical lymphadenopathy. Fine needle aspiration biopsy was taken from this nodule; cytology was assessed for compatibility with papillary thyroid carcinoma. Postsurgical pathology evaluation showed a multicentric papillary carcinoma and lymphocytic infiltration. Subacute thyroiditis, regardless of type, may produce transitory ultrasound changes that obscure the coexistence of papillary carcinoma. Due to this, initial thyroid ultrasound evaluation should be delayed until clinical recovery. We recommended a thyroid ultrasound exam for initial evaluation of painless thyroiditis, particularly in patients with palpable thyroid nodule. Further cytological examination is recommended in cases presenting with suspect thyroid nodule and/or non-nodular hypoechoic (> 1 cm) or heterogeneous areas with microcalcification focus. Arch Endocrinol Metab. 2016;60(2):178-82

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