Cytological and Ultrasound Features of Thyroid Nodules Correlate with Histotypes and Variants of Thyroid Carcinoma

Context: Prognosis is excellent for the papillary thyroid carcinoma (PTC), noninvasive follicular thyroid neoplasia with papillary-like nuclear features (NIFT-P) and the follicular thyroid carcinoma (FTC) while is poor for the poorly differentiated thyroid carcinoma (PDTC) and the anaplastic thyroid carcinoma (ATC). Among PTC, the prognosis is more favorable for the follicular (FV-PTC) and the classic (CV-PTC) than for the tall cell (TCV-PTC) and the solid (SV-PTC) variants. Objectives: To associate histotypes and variants of thyroid carcinoma with ultrasound and cytological features. Design: Histology of 1018 benign tumors and 514 PTC (249 CV, 167 FV, 49 TC, 34 SV and 15 other variants), 52 NIFT-P, 50 FTC, 11 PDTC and 3 ATC was correlated to fine-needle aspiration biopsy categories (Italian classification: TIR1, TIR2, TIR3A, TIR3B, TIR4 and TIR5) and ultrasound features. Setting: Endocrinology Unit, University Hospital of Pisa. Patients: 1117 patients with thyroid nodule(s) who underwent thyroidectomy. Intervention: None. Main outcome measure(s): None. Results: Of PTC, 36.3% had an indeterminate cytology (TIR3A or TIR3B), 56.6% suspicious for malignancy or malignant (TIR4 or TIR5); 84.0% FTC and 69.3% NIFT-P were TIR3A or TIR3B. 72.5% FV-PTC and 73.6% SV-PTC were TIR3A or TIR3B, 79.9% CV-PTC and 95.9% TCV-PTC were TIR4 or TIR5. The association of a hypoechoic pattern, irregular margins and no microcalcifications was more frequent in TCV-PTC than in CV-PTC (p=0.02, PPV=38.9%; NPV=85.5%). Conclusions: At cytology, most FTC, NIFT-P, FV-PTC and SV-PTC were indeterminate, most CV-PTC and TCV-PTC were suspicious for malignancy or malignant. Ultrasound can be helpful in ruling out TCV-PTC.