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Thyroid gland

Bethesda guidelines for Cytology

Follicular Neoplasm

Reviewer: Michael Constantinescu, M.D. (see Reviewers page)
Revised: 7 June 2013, last major update March 2011
Copyright: (c) 2010-2013, PathologyOutlines.com, Inc.


● Use if cellular aspirate of mostly follicular cells with significant crowding or microfollicle structures
● If cellular aspirates consist exclusively of Hurthle cells, designate as “Suspicious for follicular neoplasm, Hurthle cell type”
● Features of a papillary carcinoma are not included in this category
● Risk for malignancy is approximately 15-30%
● Management is usually surgical (most patients undergo hemithyroidectomy or lobectomy)


● Moderate or marked cellularity
● Cellular crowding with microfollicles and dispersed single cells
● Cells are normal size, uniform population, with scant to moderate cytoplasm, slightly hyperchromatic nuclei, inconspicuous nucleoli
● Some nuclear atypia (e.g large nuclei, prominent nucleoli)
● Scant/absent colloid
● Lesions described as "suspicious of Hurthle cell type" should consist exclusively of Hurthle cells; have abundant finely granular blue/gray-pink cytoplasm on DiffQuick or green on Pap and pink on H&E; enlarged eccentric nuclei with prominent nucleoli; virtually no lymphocytes or plasma cells

Sample reports

(1) Suspicious for a follicular neoplasm
(2) Suspicious for a follicular neoplasm
Comment: cellular aspirate composed primarily of follicular cells exhibiting a microacinar architecture
(3) Suspicious for a follicular neoplasm, Hurthle cell type

Cytology images

FNAC, follicular lesion not further specified

End of Thyroid gland > Bethesda guidelines for Cytology > Follicular Neoplasm

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