Thyroid gland
Other thyroid carcinoma
Hürthle cell (oncocytic) tumors

Author: Shahidul Islam, M.D., Ph.D. (see Authors page)

Revised: 16 February 2017, last major update March 2009

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Hurthle cell

Cite this page: Hürthle cell (oncocytic) tumors. website. Accessed October 22nd, 2017.
Definition / general
  • Follicular neoplasm in which 75% or more of follicular cells have oncocytic features and no chronic thyroiditis is present
  • Hürthle cells / oncocytes by themselves are nonspecific, and are seen in Hashimoto thyroiditis and other neoplasms
  • Tend to infarct after fine needle aspiration
  • Size is predictive; 2 cm or less - almost always adenoma; 6 cm or more - almost always carcinoma (World J Surg 2008;32:702)
  • Malignant if capsular or vascular invasion

Minimally invasive Hürthle cell carcinoma
  • 14% recur, recurrence associated with 4+ foci of vascular invasion, mitotic figures and solid / trabecular growth pattern (Cancer 2006;106:1669)
Minimally invasive Hürthle cell carcinoma
  • Also called Encapsulated Hürthle cell carcinoma
  • Usually adult women
Prognostic factors
  • Carcinomas have 5 year survival of 60 - 80%, with metastases to lung, bone and regional lymph nodes
  • Poorer prognosis if higher N / C ratio, small cell pattern, p53+ / bcl2- (Am J Surg Pathol 1996;20:686); also metastatic lymph nodes or other metastases, high stage (Eur J Surg Oncol 2009;35:230)
Case reports
  • Adenomas are cured by excision
Gross description
  • Solid, tan, encapsulated, lobulated, well vascularized
  • Invasion into adjacent tissue not apparent
Gross images

Images hosted on PathOut server:

Carcinoma, contributed by Mark R. Wick, M.D.

AFIP images:

Adenoma with massive infarct

Carcinoma has focal capsular invasion

Microscopic (histologic) description
  • At least 75% of follicular cells are oncocytic with large size, distinct cell borders, deeply eosinophilic and granular cytoplasm, large nucleus with prominent nucleolus
  • Follicular, trabecular, solid or papillary growth patterns
  • Large follicles have adjacent fibrovascular septa that resemble papillae when cut tangentially
  • May have inspissated intraluminal colloid with concentric laminations that resemble psammoma bodies, usually in lumina
  • Nuclear atypia common but not anaplasia
  • Rarely has Kaposi-like endothelial proliferation with spindle cells containing plump nuclei and focal nesting pattern, focal red blood cell extravasation, but no mitotic figures; spindle cells positive for CD31 and factor VIII, negative for keratin and thyroglobulin, (Mod Pathol 1998;11:995)
Microscopic (histologic) images

Scroll to see all images.

Images hosted on PathOut server:

Contributed by Andrey Bychkov, M.D., Ph.D.

Adenoma with atypia, contributed by Mark R. Wick, M.D.

Carcinoma images, contributed by Mark R. Wick, M.D.

Adenoma (AFIP):

Oncocytic adenoma has follicular pattern

Cytoplasm has fine, homogeneously distributed granularity

Massive infarct due to fine needle biopsy

Pseudo-angiosarcomatous pattern

Well developed papillary growth pattern

Psammoma bodies in follicular lumina

Tumor has hyalinized area near capsule

Tumor has focal cells with large hyperchromatic nuclei

Focal papillary formations

Clear cell change (AFIP):

Sharp demarcation between clear and oncocytic cells

Gradual transition from oncocytic to clear cells

Both patterns exist in same cell

Carcinoma (AFIP):

Capsular invasion

Vascular invasion

Trabecular pattern

Multinodular pattern

Nesting pattern resembles insular carcinoma

Pseudopapillary formations due to tangential sectioning

Pulmonary metastasis of tumor with trabecular growth pattern

Minimally invasive Hürthle cell carcinoma:

Fine needle biopsy induced necrosis (AFIP)

Images hosted on Flickr:

Hürthle cell adenoma, contributed by Grace C. H. Yang, M.D.

Images hosted on other servers:

Psammoma bodies in
Hürthle cell neoplasm (figure 3)


Capsular invasion

Oncocytes with abundant eosinophilic granular cytoplasm (far right pic is with intraluminal calcifications)

No capsular invasion evident

Tumor in internal jugular vein

Various images


Cells have eosinophilic cytoplasm and prominent nucleoli

Metastasis to breast

Mixed oncocytic and mucinous secreting carcinoma

Ki67, mucus secreting carcinoma

p53, mucus secreting carcinoma

Minimally invasive Hürthle cell carcinoma:

Intracapsular vascular invasion (fig. 1)

Vascular invasion (fig. 2)

Distant metastasis to femur (fig. 3)

Cytology description
  • Highly cellular, 75% or more Hürthle cells (abundant granular cytoplasm, round nuclei, often prominent nucleoli), often discohesive cells, some enlarged and pleomorphic with intracytoplasmic lumina (empty vacuoles with magenta [Diff-Quik] or green [Pap] or no material; also transgressing vessels (capillaries in clusters of Hürthle cells, Arch Pathol Lab Med 2001;125:1031)
  • No / rare colloid, lymphocytes, histiocytes, plasma cells or ordinary follicular cells
  • Cannot definitively diagnose malignancy based on cytologic material (Am J Clin Pathol 1993;100:231, Acta Cytol 2008;52:659) but malignant cases tend to have small or large cell dysplasia, nuclear crowding and discohesive cells (Diagn Cytopathol 2008;36:149)
  • Metastatic tumors may have bland cytologic features (Diagn Cytopathol 2007;35:439)
Cytology images

Images hosted on Flickr:

Hürthle cell adenoma, 10× Diff-Quik

Hürthle cell adenoma, 2× pap stain

Hürthle cell adenoma, 10× pap stain

Images hosted on other servers:

Various images

Microfollicles of carcinoma

Positive stains
Electron microscopy description
  • Numerous large mitochondria with morphologic abnormalities
Electron microscopy images

Images hosted on PathOut server:

Dilated mitochondria have reduced cristae (AFIP)

Carcinoma, contributed by Mark R. Wick, M.D.

Cytoplasm packed
with large mitochondria
with myelin figures (AFIP)

Images hosted on other servers:

Cytoplasm is packed with mitochondria

Molecular / cytogenetics description
Differential diagnosis
  • Benign thyroid lesions with prominent Hürthle cells: abundant colloid, follicular cells and histiocytes mixed with Hürthle cells
  • Papillary and medullary carcinoma may also have prominent Hürthle cells