Thyroid & parathyroid

Benign thyroid neoplasms

Hyalinizing trabecular tumor



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PubMed Search: Hyalinizing trabecular tumor

Virginia A. LiVolsi, M.D.
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Cite this page: LiVolsi VA. Hyalinizing trabecular tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/thyroidhtn.html. Accessed December 7th, 2022.
Definition / general
  • Neoplasm of follicular cells showing a trabecular growth pattern of large cells with pale to eosinophilic cytoplasm containing stromal hyaline material; the nuclear features show elongation, grooves and intranuclear inclusions (Am J Surg Pathol 1987;11:583)
Essential features
  • Trabecular architecture
  • Yellow bodies
  • MIB1 membrane staining of tumor cells
  • GLIS translocation is unique to this thyroid tumor
Terminology
  • Hyalinizing trabecular neoplasm, hyalinizing trabecular adenoma
ICD coding
  • ICD-O: 8336/0 - hyalinizing trabecular adenoma
Epidemiology
  • Hyalinizing trabecular tumor (HTT) comprises fewer than 1% of thyroid neoplasms, shows a female preponderance > 80% and occurs in adults (mean age 50 years) (Am J Surg Pathol 2008;32:1877)
Sites
  • Thyroid
Etiology
  • Unknown
Clinical features
  • HTT occurs in asymptomatic individuals and is usually an incidental finding on ultrasonography or by clinical examination
  • In approximately 30% of cases, chronic lymphocytic thyroiditis is present (Thyroid 2011;21:253)
Diagnosis
Laboratory
  • Thyroid function tests are usually within normal limits; no specific preoperative test is definitive
Prognostic factors
Case reports
Treatment
  • Surgery with removal of the affected thyroid lobe is curative
Gross description
  • Lesion is circumscribed or encapsulated without gross evidence of invasion
  • Tumor ranges in size from 5 mm - 7.5 cm; half of the tumors measure 3 cm or less
  • On section, the tumor is yellow to white in color
  • Cut surface is solid, slightly bulging and may show lobulation
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Virginia A. Livolsi, M.D.
HTT thinly encapsulated

HTT thinly encapsulated

Solid trabecular growth

Solid trabecular growth

Trabecular pattern noted

Trabecular pattern noted

Elongated nuclei

Elongated nuclei

Prominent intranuclear inclusion

Prominent intranuclear inclusion

Nuclear clearing and grooves

Nuclear clearing and grooves


Yellow bodies

Yellow bodies

Calcification in tumor stroma

Calcification in tumor stroma

Thyroglobulin stain variable

Thyroglobulin stain variable

TTF1 decorates nuclei

TTF1 decorates nuclei

Ki67 decorates membranes

Ki67 decorates membranes

Cytology description
  • Usually hypercellular smears
  • Cells radially oriented around hyaline material
  • Tumor cells elongated with abundant cytoplasm
  • Enlarged, elongated nuclei with nuclear clearing, grooves and inclusions; clearing may not be prominent
  • Cytoplasmic staining by MIB1 is characteristic
  • Stromal amorphous material may be mistaken for amyloid (Congo red stain negative)
  • Because of nuclear features and stromal deposits, cytology may be classified as either papillary carcinoma or medullary carcinoma
  • References: Am J Surg Pathol 2004;28:859, Diagn Cytopathol 2015;43:710, J Clin Pathol 2017;70:641, Cancer Cytopathol 2019;127:390
Cytology images

Contributed by Ayana Suzuki, C.T.

Nuclear pseudoinclusions

Positive stains
Negative stains
Electron microscopy description
  • Giant lysosomes are found in the cytoplasm
Molecular / cytogenetics description
Sample pathology report
  • Thyroid, right lobe, lobectomy:
    • Hyalinizing trabecular tumor, 2.5 cm nodule (see comment)
    • Comment: Specimen weighs 12 g and measures 4.2 x 2.8 x 1 cm. The surface is smooth and shows a bulging nodule in the lower portion of the lobe. On sectioning, the nodule is solid, tan and circumscribed.
Differential diagnosis
Board review style question #1

This solitary thyroid nodule represents

  1. Hyalinizing trabecular tumor
  2. Medullary thyroid carcinoma
  3. Papillary thyroid carcinoma, trabecular variant
  4. Paraganglioma
Board review style answer #1
A. Hyalinizing trabecular tumor

Comment Here

Reference: Hyalinizing trabecular tumor
Board review style question #2

The molecular signature of the tumor illustrated is

  1. BRAF K601 mutation
  2. BRAF V600E mutation
  3. GLIS rearrangement
  4. NRAS mutation
Board review style answer #2
C. GLIS rearrangement

Comment Here

Reference: Hyalinizing trabecular tumor
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