Thyroid gland
Benign neoplasms
Hyalinizing trabecular tumor

Topic Completed: 1 October 2014

Minor changes: 5 November 2019

Copyright: 2014-2019,, Inc.

PubMed Search: Hyalinizing trabecular tumor

Sheren Younes, M.D.
Page views in 2019: 8,227
Page views in 2020 to date: 3,309
Cite this page: Younes S. Hyalinizing trabecular tumor. website. Accessed June 7th, 2020.
Definition / general
  • Peculiar type of follicular cell neoplasm showing characteristic trabecular arrangement and prominent hyaline pattern
  • First described in 1987 (Am J Surg Pathol 1987;11:583), see also Am J Surg Pathol 2008;32:622
  • The vast majority have a benign course, a few cases show vascular or capsular invasion (hyalinizing trabecular carcinoma, Hum Pathol 1994;25:192)
  • Associated with chronic lymphocytic thyroiditis and multinodular goiter
  • Controversial entity, could be related to papillary thyroid carcinoma
Case reports
  • Lobectomy
Gross description
  • Yellow-tan, circumscribed
Gross images

Images hosted on PathOut server:

Lobular with white, shiny, cartilaginous elements (AFIP)

Microscopic (histologic) description
  • Trabecular pattern - trabeculae may be straight or curved giving organoid pattern
  • Elongated to polygonal cells with variable pleomorphism; cells have lightly eosinophilic cytoplasm containing hyaline material
  • Cytoplasm contains 2 - 5 micron, yellow, spherical, paranuclear cytoplasmic inclusions with clear halo of retracted cytoplasm and nuclear molding (representing giant lysosomes) in all cases (Am J Surg Pathol 1999;23:118, Arch Pathol Lab Med 2003;127:715)
  • Nuclear grooves and inclusions are common
  • Hyaline material also present in extracellular spaces
  • Psammoma bodies may be seen
  • No vascular or capsular invasion
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Dr. Mark R. Wick

AFIP Images:

Twisting trabeculae

Prominent nesting

Nuclear grooves (arrows) and pseudoinclusions (arrowhead)

Psammoma body

Intraluminal and cytoplasmic thyroglobulin

Images hosted on other servers:

Tumor cells arranged in nests

Spindle shaped cells, abundant, granular, eosinophilic cytoplasm

Vesicular chromatin distribution

Various images


Other tumors that appear similar:

Trabecular variant of papillary carcinoma

Large cytoplasmic bodies in other tumors

Cytology description
  • Smears are often bloody
  • Hypercellular smears of cohesive aggregates radially oriented around hyaline material or poorly cohesive cells
  • Have elongated or spindle cells with abundant cytoplasm, overlapping nuclei with pale chromatin, slightly enlarged nuclei, intranuclear clearing, nuclear grooves, intranuclear cytoplasmic inclusions (Am J Surg Pathol 2004;28:859)
  • Peripheral cytoplasmic pattern of MIB1 staining may be useful (Am J Clin Pathol 2004;122:506)
Cytology images

Images hosted on PathOut server:

Contributed by Ayana Suzuki, Cytotechnologist, Japan:

Nuclear pseudoinclusions

Images hosted on other servers:

Elongated tumor with acellular stroma

Positive stains
Negative stains
Electron microscopy description
  • Giant lysosomes
Molecular / cytogenetics description
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