Cytohistologic and sonographic correlation of thyroid nodules - A prospective study in a tertiary cancer centre

Background: Fine needle aspirationcytology (FNAC) reduces the number of unnecessary thyroid surgeries for patientswith benign nodules and appropriately triages patients with thyroid cancer toappropriate treatment.

Methods: This was a observational study done on casespresenting with clinical suspicion of thyroid malignancy which underwentultrasonography followed by FNAC of thyroid nodule. Ultrasonographiccharacterization of nodules was based on ThyroidImaging Reporting And Data System(TIRADS) and cytology reporting was based on Bethesda system. All recruitedpatients underwent thyroidectomy. Pre-operative cytology and ultrasonographyfeatures were compared with final histopathology report.

 Results: In ourstudy, Bethesda system of cytology reporting for thyroid nodules had a bettersensitivity, specificity and diagnostic accuracy than TIRADS system of ultrasoundreporting. Bethesda system in FNAC had a larger area under the ROC curve (0.91)as compared to ultrasound TIRADS (0.70). Malignancy rate of TIRADS 5 noduleswas 97.1% with significant p value (0.022). 100% of Bethesda VI lesions weremalignant according to final histopathology report. Ultrasound TIRADS couldpre-operatively predict malignancy in 63.6% of indeterminate thyroid noduleswith confirmed malignancy in post-operative histopathology. The overallconcordance of ultrasound TIRADS, Bethesda system and histopathology was 69.8%.

 **Conclusions:**Higher TIRADS and Bethesda scoring among thyroid nodules was associated withincreased risk of malignancy. Our study showed good concordance among USTIRADS, Bethesda system of cytology and final histopathology of thyroidnodules. US TIRADS was a good predictor of malignancy in indeterminate thyroidnodules.