The Bethesda System for Reporting Thyroid Cytopathology: Definitions, Criteria, and Explanatory Notes

Foreword
Contents
1: Overview of Diagnostic Terminology and Reporting
	Format of the Report
	References
2: Nondiagnostic
	Background
	Definition
	Criteria for Adequacy
	Nondiagnostic
	Explanatory Notes
	Management
	Sample Reports
	References
3: Benign
	Introduction
	Follicular Nodular Disease
		Background
		Definition
		Criteria
		Explanatory Notes
	Graves’ Disease
	Lymphocytic Thyroiditis
		Background
		Definition
		Criteria
	Granulomatous (de Quervain) Thyroiditis
		Criteria
	Acute Suppurative Thyroiditis
		Criteria
	Riedel Thyroiditis/Disease
		Criteria
		Explanatory Notes
		Management
		Sample Reports
	References
4: Atypia of Undetermined Significance
	Background
	Definition
	Criteria
	AUS with Nuclear Atypia
		Focal Nuclear Atypia (Fig. 4.1)
			Extensive But Mild Nuclear Atypia (Fig. 4.2)
			Atypical Cyst Lining Cells (Fig. 4.3)
			“Histiocytoid” Cells (Fig. 4.4)
			Nuclear and Architectural Atypia (Fig. 4.5)
		AUS-Other
			Architectural Atypia (Figs. 4.6, 4.7, and 4.8)
			Oncocytic/Oncocyte Atypia (Figs. 4.9 and 4.10)
			Atypia, Not Otherwise Specified (NOS) (Figs. 4.11, 4.12, and 4.13)
			Atypical Lymphoid Cells, Rule Out Lymphoma (Fig. 4.14)
	Explanatory Notes
	Management
	Sample Reports
	References
5: Follicular Neoplasm
	Background
	Definition
	Criteria for FN Cases
		Cellularity
		Architecture
		Cytoplasm
		Nuclei
			Most Common Scenario (i.e., The “Typical” FN Scenario)
			Infrequent Scenario (i.e., The “Potential NIFTP/FVPTC” Scenario)
		Other Features
	Explanatory Notes
		More About NIFTP (and FVPTC)
		Short Notes About the Molecular Features of FN and NIFTP
	Risk of Malignancy
	Differential Diagnosis of FN
	Cyto-Histologic Correlation
	Management
	Sample Reports
	References
6: Follicular Neoplasm (Oncocytic Follicular Neoplasm)
	Background
	Definition
	Criteria
	Explanatory Notes
		Minimum Necessary Criteria
			The Sparsely Cellular Specimen Composed Entirely of Oncocytes and Frequently in a Background of Blood
			The Cellular Specimen Composed Entirely of Oncocytes Without Atypia
			The Clearly Abnormal Specimen with Partial or Minimal Oncocytic Differentiation
			The Clearly Abnormal Specimen with Colloid
		Oncocytic Proliferations in Patients with Multinodular Goiter or Lymphocytic Thyroiditis
		Distinction from Other Tumors
	Management
	Sample Reports
	References
7: Suspicious for Malignancy
	Background
	Definition
	Criteria
		Suspicious for Papillary Thyroid Carcinoma
			Patchy Nuclear Changes Pattern (Figs. 7.1 and 7.2)
			Incomplete Nuclear Changes Pattern (Fig. 7.3)
			Sparsely Cellular Specimen Pattern
			Cystic Degeneration Pattern (Fig. 7.4)
		Suspicious for Medullary Thyroid Carcinoma (Figs. 7.5, 7.6, and 7.7)
		Suspicious for Lymphoma (Fig. 7.8)
		Suspicious for Malignancy, Not Otherwise Specified
	Explanatory Notes
		Suspicious for Papillary Thyroid Carcinoma
		Suspicious for Medullary Thyroid Carcinoma
		Suspicious for Lymphoma
		Suspicious for Malignancy, Not Otherwise Specified
	Management
	Role for Ancillary Studies
	Sample Reports
	References
8: Papillary Thyroid Carcinoma, Subtypes, and Related Tumors
	Background
	Conventional (Classic) Papillary Thyroid Carcinoma
		Definition
		Criteria
		Liquid-Based Preparations
		Explanatory Notes
	Subtypes (Variants) of Papillary Thyroid Carcinoma (PTC)
		Follicular Variant of PTC and NIFTP (See Also Chap. 5)
			Definitions
			Background
		How to Distinguish NIFTP from PTC on Cytology?
		Macrofollicular Variant of PTC
			Definition
			Criteria
			Explanatory Notes
		Cystic PTC
			Definition
			Criteria
			Explanatory Notes
		Oncocytic PTC
			Definition
			Criteria
			Explanatory Notes
		Warthin-Like PTC
			Definition
			Criteria
			Explanatory Notes
		Tall Cell PTC
			Definition
			Criteria
			Explanatory Notes
		Columnar Cell PTC
			Definition
			Criteria
			Explanatory Notes
		Solid/Trabecular PTC
			Definition
			Criteria
			Explanatory Notes
		Diffuse Sclerosing PTC
			Definition
			Criteria
			Explanatory Notes
		Hobnail PTC
			Definition
			Criteria
			Explanatory Notes
		Related Tumors
		Cribriform-Morular Thyroid Carcinoma
			Definition
			Criteria
			Explanatory Notes
		Hyalinizing Trabecular Tumor
			Definition
			Criteria
			Explanatory Notes
	Management
	Sample Reports
	References
9: Medullary Thyroid Carcinoma
	Background
	Definition
	Criteria
	Explanatory Notes
	Management
	Sample Reports
	References
10: High-Grade Follicular Cell-Derived Non-Anaplastic Thyroid Carcinoma
	Background
	Definition
	Criteria
	Explanatory Notes
	Molecular Genetics
	Management
	Sample Reports
	References
11: Undifferentiated (Anaplastic) Thyroid Carcinoma
	Background
	Definition
	Criteria
	Explanatory Notes
	Management
	Sample Reports
	References
12: Metastatic Tumors, Lymphomas, and Rare Tumors of the Thyroid
	Background
	Metastatic Renal Cell Carcinoma
		Criteria
		Explanatory Notes
	Metastatic Malignant Melanoma
		Criteria
		Explanatory Notes
	Metastatic Breast Carcinomas
		Criteria
		Explanatory Notes
	Metastatic Pulmonary Carcinomas
		Criteria
			Non-small Cell Carcinomas
			Small Cell Carcinomas
		Explanatory Notes
	Other Metastatic Malignancies [14]
	Lymphoma Involving the Thyroid Gland
		Criteria
		Explanatory Notes
		Extranodal Marginal Zone B-Cell Lymphoma (MALT Lymphoma)
		Diffuse Large B-Cell Lymphoma
		Hodgkin Lymphoma
	Rare Neoplasms of the Thyroid Gland
		Paraganglioma
			Definition
			Criteria
			Explanatory Notes
		Langerhans Cell Histiocytosis
			Definition
			Criteria
			Explanatory Notes
		Mucoepidermoid Carcinoma
			Definition
			Criteria [29, 30]
			Explanatory Notes
		Sclerosing Mucoepidermoid Carcinoma with Eosinophilia (SMECE)
			Definition
			Criteria [31, 32]
			Explanatory Notes
		Secretory Carcinoma of the Thyroid
			Definition
			Criteria
			Explanatory Notes
		Ectopic Thymoma
			Definition
			Criteria [35–38]
				Type A Thymoma (Fig. 12.22)
				Type B Thymoma (Fig. 12.23)
			Explanatory Notes
		Spindle Epithelial Tumor with Thymus-Like Differentiation (SETTLE)
			Definition
			Criteria [39–41]
			Explanatory Notes
	Other Rare Primary Neoplasms of the Thyroid Gland
	Management
	Sample Reports
	References
13: Clinical Perspectives and Imaging Studies
	Background: Thyroidology
		Risk Stratification with Ultrasound
		TI-RADS: Definition and Aims
		Indications for FNA
		Challenges of the Cytopathologist in the Era of TI-RADS. What Is Expected from the Cytopathologist for each TI-RADS Score?
		Management of Nodules Post-FNA
	References
14: Molecular and Other Ancillary Tests
	Background
	Overview of Molecular Changes in Thyroid Neoplasia
		DNA-Level Alterations
		Gene (mRNA) and microRNA Expression Alterations
	Current and Emerging Roles of Molecular Testing for Thyroid FNA Specimens
		Refining Cancer Probability in Nodules Classified as AUS and FN
		Prognostication of Tumors Based on Molecular Profiles
		Identification of Systemic Therapy and/or Clinical Trials Tailored to a Tumor’s Molecular Profile
		Screening for Germline Alterations Associated with Hereditary Syndromes
	Molecular Testing Platforms Available for Thyroid FNA Specimens
		Tests for Oncogenic Mutations and Gene Fusions
		Combined Testing Platforms Offered by Reference Laboratories
	Conclusions and Future Directions
	Sample Reports
	References
Correction to: Atypia of Undetermined Significance
	Correction to: Chapter 4 in: S. Z. Ali, P. A. VanderLaan (eds.), The Bethesda System for Reporting Thyroid Cytopathology, https://doi.org/10.1007/978-3-031-28046-7_4
Index