HYALINIZING TRABECULAR CARCINOMA OF THE THYROID-GLAND - REPORT OF 2 CASES OF FOLLICULAR CELL THYROID-CARCINOMA WITH HYALINIZING TRABECULAR PATTERN

Recently tumors have been reported that have an architectural pattern and cellularity similar to hyalinizing trabecular adenoma and show eit her parafollicular differentiation or histological findings suggestive of malignant neoplasm of the follicular cells. This study describes t wo cases of thyroid carcinoma of follicular cells that displayed a hyl inizing trabecular pattern. The first case was a 25-year-old euthyroid woman with a cold thyroid nodule in the right lobe. On fine needle as piration a diagnosis of papillary carcinoma was rendered. The thyroide ctomy disclosed a 2-cm, firm, brown, encapsulated tumor in the right l obe. The tumor had a growth pattern and cytologic features similar to those described in hyalinizing trabecular adenoma. The differences bet ween these neoplasms were the presence of mitotic figures, prominence of the nucleolus, capsular blood vessel invasion, and microtubule grou ps in the endoplasmic reticulum. The second case was a 19-year-old eut hyroid woman with a cold thyroid nodule in the left lobe. A cytologic diagnosis of follicular proliferation was rendered. A 4-cm, firm, whit ish, encapsulated nodule was found in the left lobectomy. The tumor ce lls were arranged in two clear-cut patterns: a trabecular hyalinizing pattern with a small focus of papillary growth, and a follicular patte rn. These findings confirm the existence of malignant thyroid tumors w ith a hyalinizing trabecular pattern and illustrate the nonspecificity of this peculiar pattern, since it may also be seen in papillary carc inomas of the thyroid. The relationship between hyalinizing trabecular adenoma and papillary carcinoma of the thyroid is commented on.