Paraganglioma-like (hyalinizing trabecular) adenoma of the thyroid revisited

The aim of the present study was to explore the association between paraganglioma-like adenomas of the thyroid (PLAT) and chronic lymphocytic thyroiditis (CLT) or Hashimoto's thyroiditis, and to discuss its possible relationship to papillary thyroid carcinoma. Six cases were analyzed by standard histopathological and immunohistochemical techniques. All 6 cases (all females) had clinical and/or histological evidence of CLT. Only one patient had 2 PLATs. The PLATs were devoid of inflammation and sharply demarcated from the surrounding CLT. There is cyto-morphological overlap with papillary thyroid carcinoma (nuclear grooves and pseudo-inclusions). We conclude that PLAT is associated with CLT more frequently than any other thyroid lesion, and feel that this is more than merely a chance association. PLAT shares several cytological features with papillary carcinoma and cases have been seen where they have occurred in the same thyroid. PLAT could therefore represent an unusual variant of papillary carcinoma.