Impact of the Italian Society of Anatomic Pathology and Diagnostic Cytology Classification of Thyroid Nodules in the Treatment of Indeterminate Follicular Lesions: Five-Year Results at a Single Center

Table 1

Comparison of the Bethesda, the RCPath, and the SIAPEC diagnostic categories.

BSRTC	RCPath	SIAPEC
I. Nondiagnostic or unsatisfactory	THY1/THY1c. Nondiagnostic /Cystic	TIR1. Nondiagnostic; TIR1C : Nondiagnostic cystic
II. Benign	THY2/THY2c. Nonneoplastic	TIR2 : Nonmalignant /benign
III. Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS)	THY3a. Neoplasm possible. Atypical features present but not enough to place into any of the other categories	TIR3A. Low-risk indeterminate lesion
IV. Follicular neoplasm or suspicious for a follicular neoplasm	THY3f. Neoplasm possible—suggesting follicular neoplasm	TIR3B. High-risk indeterminate lesion
V. Suspicious for malignancy	THY4. Suspicious of malignancy	TIR4. Suspicious of malignancy
VI. Malignant	THY5. Malignant	TIR5. Malignant