Thyroid & parathyroid

Benign thyroid neoplasms

Hyalinizing trabecular tumor

Topic Completed: 1 October 2014

Minor changes: 28 April 2021

Copyright: 2014-2021,, Inc.

PubMed Search: Hyalinizing trabecular tumor

Sheren Younes, M.D.
Page views in 2020: 8,473
Page views in 2021 to date: 8,105
Cite this page: Younes S. Hyalinizing trabecular tumor. website. Accessed October 15th, 2021.
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

AFIP images

Lobular with white, shiny, cartilaginous elements

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

Contributed by Mark R. Wick, M.D.

AFIP images

Twisting trabeculae

Prominent nesting

Nuclear grooves (arrows) and pseudoinclusions (arrowhead)

Psammoma body

Intraluminal and cytoplasmic thyroglobulin

Images hosted on other servers:

Spindle shaped cells, abundant, granular, eosinophilic cytoplasm

Vesicular chromatin distribution

Various images


Other tumors that appear similar:

Trabecular variant of papillary carcinoma

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

Contributed by Ayana Suzuki, C.T.

Nuclear pseudoinclusions

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