Hyalinizing trabecular carcinoma of the thyroid gland: report of two cases of follicular cell thyroid carcinoma with hyalinizing trabecular pattern.
ABSTRACT Recently tumors have been reported that have an architectural pattern and cellularity similar to hyalinizing trabecular adenoma and show either parafollicular differentiation or histological findings suggestive of malignant neoplasm of the follicular cells. This study describes two cases of thyroid carcinoma of follicular cells that displayed a hylinizing trabecular pattern. The first case was a 25-year-old euthyroid woman with a cold thyroid nodule in the right lobe. On fine needle aspiration a diagnosis of papillary carcinoma was rendered. The thyroidectomy disclosed a 2-cm, firm, brown, encapsulated tumor in the right lobe. The tumor had a growth pattern and cytologic features similar to those described in hyalinizing trabecular adenoma. The differences between these neoplasms were the presence of mitotic figures, prominence of the nucleolus, capsular blood vessel invasion, and microtubule groups in the endoplasmic reticulum. The second case was a 19-year-old euthyroid woman with a cold thyroid nodule in the left lobe. A cytologic diagnosis of follicular proliferation was rendered. A 4-cm, firm, whitish, encapsulated nodule was found in the left lobectomy. The tumor cells were arranged in two clear-cut patterns: a trabecular hyalinizing pattern with a small focus of papillary growth, and a follicular pattern. These findings confirm the existence of malignant thyroid tumors with a hyalinizing trabecular pattern and illustrate the nonspecificity of this peculiar pattern, since it may also be seen in papillary carcinomas of the thyroid. The relationship between hyalinizing trabecular adenoma and papillary carcinoma of the thyroid is commented on.
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ABSTRACT: The hyalinizing trabecular tumor (HTT) is an unusual tumor of the thyroid gland and controversial lesion. They are thyroid lesions with prominent sclerosis or hyalinization and trabecular architecture and they share several histologic, immunohistochemical and molecular features with another thyroid neoplasms like papillary thyroid carcinoma (PTC). Cytoplasmic yellow bodies are a common and frequent histological finding in hyalinizing trabecular adenoma. Membrane and cytoplasmic immunopositivity for the monoclonal antibody MIB-1 is characteristic. In this article we report a novel expression with Ki-67 immunoreactivity in cytoplasmic and paranuclear bodies. A review of literature is included.Revista Española de Patología. 01/2009; 42(1).
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ABSTRACT: The most common thyroid neoplasms are either follicular derived (papillary, follicular and Hürthle cell lesions) or C-cell derived (medullary carcinoma). The diagnosis of these tumors can usually be made at the histologic level, with immunohistochemical stains necessary in some circumstances. Specific molecular mutations have been described that can be diagnostically useful or explain, in part, their pathogenesis, including the well-known Ret/PTC and PPARgamma-PAX8 translocations, point mutations in the Ret, Ras and BRAF genes, and loss of heterozygosity of multiple different tumor suppressor genes. Some unusual tumors of the thyroid gland are more difficult to diagnose. In examining these lesions, the pathologist may use the hematoxylin and eosin-stained morphology, coupled with an analysis of the immunohistochemical staining profiles and possibly analysis of the underlying molecular mutational patterns. These less common thyroid tumors include tall cell and cribriform-morular variants of papillary carcinoma, hyalinizing trabecular tumor, mucoepidermoid and sclerosing mucoepidermoid carcinoma with eosinophilia, poorly differentiated (insular) carcinoma, and undifferentiated (anaplastic) carcinoma. The diagnostic features of these rare tumors, including the histology, immunohistochemical expression profiles and the known molecular mutational profiles of each, are reviewed.Expert Review of Molecular Diagnostics 10/2005; 5(5):725-34. · 4.09 Impact Factor