Hyalinising trabecular tumour of the thyroid (HTT, hyalinizing trabecular adenoma, paraganglioma-like adenoma of the thyroid, PLAT)

This tumour appears to have been described independently on four occasions, beginning with that of Zipkin under the tutelage of Langhans in 190510.

The histogenesis of this tumour is debated. Morphological similarities and rearrangement of the RET( rearranged during transfection) proto-oncogene1,6,9 suggest affinity to papillary carcinoma.

Epidemiology

HTT is a rare thyroid neoplasm10. It is typically a tumour of midle-aged women.

Clinical features

HTT is typically a tumour of middle-aged women.

Histopathology

These tumours are circumscribed. They consist of elongated cells growing in a trabecular pattern, surrounded by dense hyaline material. Nuclei show grooves and pseudoinclusions. The cytoplasm contains characteristic paranuclear refractile pale (yellow) bodies8. The stroma may calcify, resembling psammoma-bodies. This stromal material resembles amyloid but is negative with a Congo Red stain. It is diastase-resistant periodic acid-Schiff positive and stains for collagen IV and laminin7.

Immunohistochemistry

RET	4/141
CK19	variable results2,3,4
High MW cytokeratin	0/124
Ki-67 (MIB-1)	15/15, cytoplasmic positivity5
thyroglobulin	12/123
calcitonin	0/123
thyroperoxidase	3/123

Differential diagnosis

follicular adenoma, may have a hyalinising trabecular pattern, but is negative for RET.
medullary carcinoma
papillary thyroid carcinoma: both show nuclear pseudoinclusions and grooves. Cases showing both tumours in the same patient have been reported. Papillary carcinomas do NOT show cytoplasmic staining with MIB-15.
poorly differentiated (trabecular/insular) carcinoma
paraganglioma

Prognosis

Carney regards the great majority of these tumours as benign, with very rare cases of hyalinising trabecualr carcinoma showing malignant behaviour10.

References

1 Papotti M, Volante M, Giuliano A et al. RET/PTC Activation in Hyalinizing Trabecular Tumors of the Thyroid. Am J Surg Path 2000;24:1615-1621.

2 Fonseca, E., Nesland, J. M., Sobrinho-Simoes, M. Expression of stratified epithelial-type cytokeratins in hyalinizing trabecular adenomas supports their relationship with papillary carcinomas of the thyroid. Histopathology 1997;31:330-5.

3 Papotti, M., Riella, P., Montemurro, F., Pietribiasi, F., Bussolati, G. Immunophenotypic heterogeneity of hyalinizing trabecular tumours of the thyroid. Histopathology 1997;31:525-33.

4 Hirokawa, M., Carney, J. A. Ohtsuki, Y. Hyalinizing trabecular adenoma and papillary carcinoma of the thyroid gland express different cytokeratin patterns. Am J Surg Pathol 2000;24:877-881.

5 Hirokawa, M, Carney, J. A. Cell membrane and cytoplasmic staining for MIB-1 in hyalinizing trabecular adenoma of the thyroid gland. Am J Surg Pathol 2000;24:575-578.

6 Cheung, C. C., Boerner, S. L., MacMillan, C. M. Hyalinizing trabecular tumor of the thyroid: a variant of papillary carcinoma proved by molecular genetics. Am J Surg Pathol 2000;24:1622-6.

7 Katoh, R., Kakudo, K., Kawaoi, A. Accumulated basement membrane material in hyalinizing trabecular tumors of the thyroid. Mod Pathol 1999;12:1057-61.

8 Rothenberg, H. J., Goellner, J. R., Carney, J. A. Hyalinizing trabecular adenoma of the thyroid gland: recognition and characterization of its cytoplasmic yellow body. Am J Surg Pathol 1999;23;118-25.

9 Lloyd, R. V. Hyalinizing trabecular tumors of the thyroid: a variant of papillary carcinoma? Adv Anat Pathol 2002;9:7-11.

10 Hyalinizing Trabecular Tumors of the Thyroid Gland: Quadruply Described But Not by the Discoverer Carney AJSP 2008;32:622

This page last revised 15.4.2008.