PARAGANGLIOMA-LIKE (HYALINIZING TRABECULAR) ADENOMA OF THE THYROID REVISITED

The aim of the present study was to explore the association between pa raganglioma-like adenomas of the thyroid (PLAT) and chronic lymphocyti c thyroiditis (CLT) or Hashimoto's thyroiditis, and to discuss its pos sible relationship to papillary thyroid carcinoma. Six cases were anal yzed by standard histopathological and immunohistochemical techniques. All 6 cases (all females) had clinical and/or histological evidence o f CLT. Only one patient had 2 PLATs. The PLATs were devoid of inflamma tion and sharply demarcated from the surrounding CLT. There is cyto-mo rphological overlap with papillary thyroid carcinoma (nuclear grooves and pseudo-inclusions). We conclude that FLAT is associated with CLT m ore frequently than any other thyroid lesion, and feel that this is mo re than merely a chance association. FLAT shares several cytological f eatures with papillary carcinoma and cases have been seen where they h ave occurred in the same thyroid. FLAT could therefore represent an un usual variant of papillary carcinoma.