Thyroid gland
Cytology
Bethesda system
Hürthle cell neoplasm


Topic Completed: 7 May 2020

Minor changes: 14 September 2020

Copyright: 2020, PathologyOutlines.com, Inc.

PubMed Search: Hurthle cell neoplasm [title]

Ayana Suzuki, C.T.
Andrey Bychkov, M.D., Ph.D.
Page views in 2020 to date: 2,883
Cite this page: Suzuki A, Bychkov A. Hürthle cell neoplasm. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/thyroidhurthlecellneoplasm.html. Accessed October 24th, 2020.
Definition / general
  • Bethesda category IV - Hürthle, “follicular neoplasm, Hürthle cell type / suspicious for a follicular neoplasm, Hürthle cell type (FNHCT/SFNHCT)” is used for cases with a cellular aspirate that consists exclusively of Hürthle cells (Thyroid 2017;27:1341)
  • Hürthle cells are thyroid follicular cells with oncocytic appearance characterized by large hyperchromatic nuclei with prominent nucleoli and abundant granular eosinophilic cytoplasm
  • Cases cytologically suspected for Hürthle cell adenoma and Hürthle cell carcinoma are included
    • The final diagnosis is made histologically because capsular or vascular invasion are the essential criteria of Hürthle cell carcinoma
Essential features
  • Includes cases with most of the follicular cells showing abundant fine granular cytoplasm (Hürthle cells)
  • Frequency 1.2 - 8.75%, resection rate 30.1%, risk of malignancy 10 - 40%
  • The most common histopathological diagnosis is Hürthle cell adenoma and Hürthle cell carcinoma, followed by multinodular goiter and Hashimoto thyroiditis
Terminology
  • The term “suspicious for a follicular neoplasm, Hürthle cell type (SFNHCT)” may be more convenient than “follicular neoplasm, Hürthle cell type (FNHCT)” because some nodular goiter or Hashimoto thyroiditis (i.e. nontumor) cases are included in this category
  • Hürthle cells are also known as oxyphilic, oncocytes or Askanazy cells (Oncologist 2011;16:1380)
  • In the Bethesda System for Reporting Thyroid Cytopathology, FNA specimens that are suspicious for a Hürthle cell neoplasm are distinguished from those suspicious for a non-Hürthle cell follicular neoplasm (Ali: The Bethesda System for Reporting Thyroid Cytopathology, 2nd Edition, 2018)
    • Striking morphologic difference between the cytologic patterns of follicular and Hürthle cell neoplasms
    • Follicular and Hürthle cell carcinomas may be genetically different neoplasms (Onco Targets Ther 2016;9:6873)
    • WHO histological classification also has a separate chapter for Hürthle (oncocytic) cell tumors
Clinical features
Diagnosis
  • Aspirates are at least moderately cellular and are composed exclusively of Hürthle cells
  • Aspirates composed entirely of Hürthle cells with abundant fine granular cytoplasm should be diagnosed as FNHCT/SFNHCT
  • Excluded from this category:
Case reports
Cytology description
  • Abundant finely granular cytoplasm
    • Blue or gray pink (Romanowsky), green (Papanicolaou), pink (H&E)
  • Nuclei
    • Round
    • Enlarged, central or eccentrically located
    • Prominent nucleolus
    • Binucleation (common)
  • Small cells with high nuclear / cytoplasmic (N/C) ratio (small cell dysplasia) (Cancer 2002;96:261)
  • Large cells with more than two times anisonucleosis (large cell dysplasia) (Cancer 2002;96:261)
  • Predominantly isolated cells but sometimes arranged in crowded, syncytial-like clusters
  • Little or no colloid
  • No lymphocytes or plasma cells
  • Transgressing vessels (capillaries passing through clusters of Hürthle cells), seen occasionally (Arch Pathol Lab Med 2001;125:1031)
  • Sometimes intracytoplasmic colloid inclusions (Arch Pathol Lab Med 2001;125:1031)
Cytology images

Contributed by Ayana Suzuki, C.T.

Follicular neoplasm, Hürthle cell type

Hürthle cell clusters

Oncocytes and histiocytes


Contributed by Grace C.H. Yang, M.D.

Hürthle cell adenoma, Diff-Quik

Hürthle cell adenoma, Pap stain

Hürthle cell adenoma, Pap stain

Treatment
Sample cytology report
  1. Dx / category: follicular neoplasm, Hürthle cell (oncocytic) type
    • Cellular aspirate consisting of abundant isolated oncocytes in the absence of colloid
  2. Dx / category: suspicious for a follicular neoplasm, Hürthle cell (oncocytic) type
    • Cellular aspirate of follicular cells with Hürthle cell features, in addition occasional nuclear grooves and focal papillary architecture are seen
    • The findings raise the possibility of a Hürthle cell neoplasm with mild nuclear irregularity but a papillary carcinoma cannot be excluded
  3. Dx / category: suspicious for a follicular neoplasm, Hürthle cell (oncocytic) type
    • Cellular aspirate composed of cells with abundant granular cytoplasm
    • The findings raise the possibility of a Hürthle cell neoplasm but a parathyroid tumor cannot be excluded
    • Correlation with clinical findings, imaging and biochemistry might be helpful
Videos

Case 1

Case 2

Differential diagnosis
Board review style question #1
Which finding is not helpful in distinguishing medullary carcinoma from a Hürthle cell neoplasm?

  1. Salt and pepper chromatin
  2. Metachromasia in Romanowsky stain
  3. Calcitonin measurement using needle washout fluid
  4. PTH value measurement using needle washout fluid
  5. Calcitonin immunostaining
Board review answer #1
D. PTH value measurement using needle washout fluid; PTH value measurement is useful for parathyroid lesions

Reference: Hürthle cell neoplasm

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Board review style question #2
What is the most likely diagnosis of this thyroid aspirate?



  1. Chronic thyroiditis
  2. Adenomatous nodule
  3. Hürthle cell neoplasm
  4. Medullary carcinoma
  5. Parathyroid adenoma
Board review answer #2
D. Medullary carcinoma; salt and pepper chromatin indicates medullary carcinoma

Reference: Hürthle cell neoplasm

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