Case 98 - Discussion

Uploaded: 2007-09-18, Updated: 2007-10-01


This is an outside consultation case and was originally diagnosed as "Papillary Carcinoma, Follicular Variant with Tall Cell Morphology". Personally, I feel the best diagnosis could be "Hylanizing trabecular adenoma (HTA)":


Hylanizing trabecular adenoma (HTA)

  • No capsule but normally sharply circumscribed;

  • Highly nested/trabecular pattern of growth;

  • Prominent intracellular and extracellular deposition of pink glassy collagen;

  • The stroma may have degenerative changes including calicification;

  • Enlarged and elongated nuclei with longitudinal grooves and prominent inclusions.

Similarities between HTA and papillary thyroid cancer (PTC)

  • Psammoma-like calcifications and pseudopapillary formations;

  • May show similar nuclear features: elongation, chromatin clearing, intranuclear inclusions;

  • Share the similar genetic alterations.

Therefore, the true nature of HTA is uncertain, including adenoma, low-grade tumor or a specific variant of PTC. However, regardless of these arguments, the prognosis of HTA is excellent.


  • Rosai and Ackerman's Surgical Pathology, 9th Edition