Diagnostic Accuracy of Ultrasound and Fine-Needle Aspiration Cytology in Thyroid Malignancy.

Introduction: Thyroid nodule incidence is increasing due to the widespread application of ultrasonography. Fine-needle aspiration cytology is widely applied for the detection of malignancies. The aim of this study was to evaluate the predictive value of ultrasonography in thyroid cancer. Methods: This retrospective study included patients that underwent total thyroidectomy for benign thyroid disease or well-differentiated thyroid carcinoma from January 2017 to December 2022. The study population was divided into groups: the well-differentiated thyroid cancer group and the control group with benign histopathological reports. Results: In total, 192 patients were enrolled in our study; 159 patients were included in the well-differentiated thyroid cancer group and 33 patients in the control group. Statistical analysis demonstrated that ultrasonographic findings such as microcalcifications (90.4%), hypoechogenicity (89.3%), irregular margins (92.2%) and taller-than-wide shape (90.5%) were correlated to malignancy (p < 0.001). Uni- and multivariate analysis revealed that both US score (OR: 2.177; p < 0.001) and Bethesda System (OR: 1.875; p = 0.002) could predict malignancies. In terms of diagnostic accuracy, the US score displayed higher sensitivity (64.2% vs. 33.3%) and better negative predictive value (34.5% vs. 24.4%) than the Bethesda score, while both scoring systems displayed comparable specificities (90.9% vs. 100%) and positive predictive values (97.1% vs. 100%). Discussion: The malignant potential of thyroid nodules is a crucial subject, leading the decision for surgery. Ultrasonography and fine-needle aspiration cytology are pivotal examinations in the diagnostic process, with ultrasonography demonstrating better negative predictive value.

Thyroid sarcoidosis: a rare entity in the differential diagnosis of thyroid cancer.

SUMMARY: We present two cases of thyroid sarcoidosis that were misdiagnosed as thyroid cancer. In the first patient, fine needle aspiration cytology (FNAc) of a suspicious thyroid nodule indicated the presence of papillary thyroid cancer, and the patient underwent thyroid surgery. However, histopathology identified a sarcoid granuloma, without any sign of malignancy. The second patient had a history of papillary microcarcinoma with suspicious lymph nodes diagnosed years after the initial diagnosis and was referred for assessment of cervical lymphadenopathy. Fine needle aspiration cytology (FNAc) of the suspicious lymph nodes erroneously indicated metastasis from thyroid cancer, and lateral modified lymph node dissection was performed, based on FNAc and ultrasonographic features. Histopathology excluded malignancy and identified non-caseating granulomas. Sarcoidosis of the thyroid may have a clinical presentation similar to well-differentiated thyroid carcinoma and, although rare, should be considered in the differential diagnosis, especially when other signs of the disease are already present. In these cases, FNAc provided a false diagnosis of papillary thyroid carcinoma and lymph node metastases that led to unnecessary surgery. LEARNING POINTS: Sarcoidosis may share clinical and ultrasonographic features with papillary thyroid carcinoma. Fine needle aspiration cytology is helpful in the diagnosis of both conditions; however, the overlapping cytological characteristics may lead to erroneous diagnosis. The present cases illustrate the importance of cytological identification of these difficult cases. Every piece of information provided by the clinician is essential to the cytologist.