Multimodal Diagnostic Cross-Check: A Correlative Study of Fine-Needle Aspiration Cytology, Ultrasonography, Thyroid Profile, and Histopathology in Thyroid Swellings.

BACKGROUND

Thyroid swellings are common in surgical and endocrine practice, and accurate preoperative discrimination of benign from malignant nodules guides surgical decision-making and avoids unnecessary intervention. Preoperative work-up typically combines fine-needle aspiration cytology (FNAC), ultrasonography (USG) with Thyroid Imaging Reporting and Data System (TI-RADS) scoring, and serum thyroid-stimulating hormone (TSH) measurement, with histopathological examination (HPE) as the reference standard.

OBJECTIVES

To evaluate the diagnostic performance and correlation of FNAC (Bethesda System), the American College of Radiology (ACR) TI-RADS USG, and serum TSH status against histopathological examination as the reference standard.

METHODS

In this single-center, prospective, cross-sectional study conducted from June 2024 to May 2025, 178 consecutive patients underwent clinical evaluation, serum TSH measurement, USG using ACR TI-RADS, and FNAC, with results reported according to the Bethesda System. Sixty-eight patients (38.20%) underwent surgery, with HPE as the reference standard. Diagnostic performance estimates were calculated only in this surgically verified subgroup, with 95% Wilson score confidence intervals (CIs).

RESULTS

The mean age was 44.88 ± 15.34 years. Of the 178 patients, 108 (60.67%) were female (female-to-male ratio, 1.54:1). Hypothyroidism was the most common thyroid functional state, occurring in 103 (57.87%) patients. Among the 68 operated patients, malignant or borderline histopathology, including non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), was confirmed in 36 (52.94%) patients. FNAC showed sensitivity of 58.33%, specificity of 100.00%, positive predictive value (PPV) of 100.00%, negative predictive value (NPV) of 68.09%, and accuracy of 77.94% (κ = 0.57). USG showed sensitivity of 75.00%, specificity of 78.12%, PPV of 79.41%, NPV of 73.53%, and accuracy of 76.47% (κ = 0.53). The Bethesda category correlated strongly with HPE (χ² = 50.43, P < 0.0001); thyroid functional status did not (P = 0.309).

CONCLUSIONS

Within the surgically verified subgroup, FNAC and USG TI-RADS provided complementary diagnostic information. FNAC showed high specificity and PPV but limited sensitivity, whereas USG TI-RADS showed higher sensitivity with lower specificity. Interpretation is limited by partial histopathological verification.