5. 3. Risk of malignancy (ROM) estimates have been refined.
(incorporating more extensive published data since the second
edition of TBSRTC)
4. More formalized subcategorization of AUS (based on ROM: AUS
with nuclear atypia vs. AUS-other
6. 5. All high-grade follicular-derived carcinomas, including poorly
differentiated thyroid carcinoma (PDTC) and differentiated high-
grade thyroid carcinoma (DHGTC).. Included in the chapters
12. ADEQUACY CRITERIA
• At least six groups of well-visualized (i.e., well stained,
undistorted, and unobstructed) benign follicular cells
• Each group composed of at least 10 cells
• These six groups of ten follicular cells could be either on one
slide or distributed among several for adequacy determination
13. EXCEPTIONS
Colloid nodules:
Any specimen that contains abundant colloid is adequate
(and benign)
Solid nodules with inflammation: Whenever a specific diagnosis
(e.g., lymphocytic thyroiditis, thyroid abscess, granulomatous
thyroiditis) can be rendered
Solid nodules with cytologic atypia: whenever there is any
significant atypia
14. II. BENIGN
• Consistent with a follicular nodular disease (includes
adenomatoid nodule, colloid nodule, etc.)
• Consistent with chronic lymphocytic (Hashimoto) thyroiditis in
the proper clinical context
• Consistent with granulomatous (subacute) thyroiditis
15. • Cytologic sample that is adequate for evaluation and consists of
colloid and benign-appearing follicular cells in varying
proportions.
16. III. ATYPIA OF UNDETERMINED SIGNIFICANCE
• TBSRTC 2023 discontinues the term ‘‘follicular lesion of
undetermined significance’’
• AUS is one of the three ‘‘indeterminate’’ cytopathologic
interpretations that convey a diagnosis that is not definitively
benign or malignant.
17. • “Atypia of Undetermined Significance” (AUS) is reserved for -
one or more of a heterogeneous group of findings.
• That raise concern for neoplasm/malignancy but are insufficient
to be classified as a follicular neoplasm, suspicious for
malignancy, or malignant.
18. An important change in this category
• Atypia in AUS has been categorised as: nuclear and other (which
includes architectural, oncocytic, lymphoid and NOS categories)
• The term cytologic atypia is no longer used.
• AUS aspirates with nuclear atypia: twofold higher ROM
19. AUS are now subclassified into two broad subcategories
• AUS with nuclear atypia: raises a low level of concern for
papillary carcinoma or NIFTP
• AUS—Other: in which other (non-nuclear) features result in AUS
interpretation are
Architectural atypia, Oncocytic atypia, Atypical lymphoid cells,
Atypia NOS
20.
21.
22. Architectural atypia
a). -Scantly cellular specimen with rare clusters of follicular cells,
• Almost entirely in microfollicles or crowded three-dimensional
groups and with scant colloid
• Focally prominent microfollicles with minimal nuclear atypia
(Intrathyroid Parathyroid adenoma)
23.
24. Moderately to markedly cellular specimen
• Exhibits architectural atypia in most follicular cells but without a
marked predominance (at least 70% of follicular cells) that
would warrant a FN diagnosis.
25. ATYPIA, NOT OTHERWISE SPECIFIED (NOS)
• A minor population of follicular cells shows nuclear
enlargement, often accompanied by prominent nucleoli
• Does not raise concern for papillary carcinoma
26. A). Graves’ disease treated with methimazole show marked nuclear
enlargement and anisonucleosis
(b) Atypical follicular cells from a patient with a history of ionizing
radiation to the neck
27. • AUS/FLUS is an interpretation of last resort and should be used
judiciously.
• Mixed, but predominantly macrofollicular, architectural patterns are
best classified as benign
• Some Hürthle cells or cyst-lining cells, with mild nuclear alterations
(e.g., nuclear grooves, finely granular or pale chromatin)
• Does not warrant an AUS/FLUS designation if there is ample evidence
of benign follicular cells and abundant colloid
28. IV. FOLLICULAR NEOPLASM
• TBSRTC 2023 recommends discontinuing the use of term
‘‘suspicious for a follicular neoplasm
• Intended for those aspirates that are at least moderately cellular
and composed of follicular cells
• Most of which show significant architectural abnormality in the
form of microfollicles and/or crowding, trabeculae, or single
cells.
29. Overlapping cytologic features between various follicular-patterned
lesions
• Follicular nodular disease
• Follicular adenoma
• FVPTC
• Follicular thyroid carcinoma
• NIFTP
30. • NIFTP cases in thyroid FNAs is important to avoid overdiagnosing them
as‘‘malignant—papillary thyroid carcinoma’’ or ‘‘suspicious for malignancy.
• Suspicious for papillary thyroid carcinoma, ’’diagnostic categories that
could unnecessarily result in aggressive surgical procedures
• The recommended treatment for NIFTP is conservative surgery.
31. • Follicular-patterned aspirates with only mild nuclear changes (i.e., mild
degree of enlargement, contour irregularity, and/or chromatin clearing) are
best classified as follicular neoplasm
• If true papillae are absent and intranuclear pseudoinclusions are either
absent or very rare.
• Because the reporting category name is now simply ‘‘follicular neoplasm’’
and not ‘‘suspicious for a follicular neoplasm.
• The recommended management of follicular neoplasm is surgical excision
of the nodule, most often hemithyroidectomy or lobectomy.
32.
33. • “MICROFOLLICLE” designation must be limited to crowded, flat
or 3 dimensional groups of less than 15 follicular cells
• Arranged in a circle that is at least two-thirds complete
• An important defining feature of the microfollicle is the
crowding and overlapping of the follicular cell
34. • A virtually exclusive population of oncocytes
• usually scant to absent colloid,
• Rare to absent background lymphocytes
• Often, with the presence of nuclear and cellular size variations.
• All comes under follicular neoplasm.
35. V. SUSPICIOUS FOR MALIGNANCY
• Cytomorphologic features of a thyroid FNA are worrisome for papillary
thyroid carcinoma, medullary thyroid carcinoma, lymphoma, or another
malignant neoplasm
• But are quantitatively and/or qualitatively insufficient for a definitive
malignant
36. • Sample is moderately or highly cellular.
• Follicular cells (arranged predominantly in sheets and/or
macrofollicular fragments)
• Admixed with cells that have nuclear enlargement, nuclear
pallor, limited nuclear grooves, nuclear membrane irregularity,
and/or nuclear molding.
• Intranuclear pseudoinclusions (INPIs) are very few or absent,
and psammoma bodies and papillary architecture are absent.
37. Sheet of follicular cells
including nuclear
enlargement, powdery
chromatin, nuclear
membrane irregularity,
nuclear grooves and
molding, and small
nucleoli.
