Background: Primary cilia (PC) are conserved structures in the adult thyroid gland of different mammals. We have recently described that, in humans, PC are usually present as a single copy per follicular cell emerging from the follicular cell apex into the follicular lumen. Methods: To better understand the role developed by PC in thyroid hormonogenesis, we investigated their changes in different human functional thyroid diseases (diffuse toxic hyperplasia/ Grave's disease and nodular hyperplasia/nodular goiter), in comparison with normal thyroid tissue, using immunofluorescence, morphometry and electron microscopy analyzes. Results: We found significantly decreased ciliary frequencies in both nodular hyperplasia (51.16±11.69%) and Grave's disease (44.43±23.70%) vs. normal thyroid glands (76.09±7.31%). Similarly, PC lengths were also significantly decreased in both nodular hyperplasia (2.02±0.35 µm) and Grave's disease (2.42±0.48 µm) compared to normal glands (3.93±0.90 µm). Moreover, in Grave's disease patients, hyperactive-follicle foci always showed diminished ciliary frequency and length compared to any other thyroid follicle pattern, independent of their thyroid status. Conclusions: Our results suggest a direct relationship between ciliogenesis and both follicle activity and tissue heterogeneity. Furthermore, the Thyroid

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.

The response of parathyroid cells to serum calcium is regulated by a calcium-sensing receptor protein (CaR). In patients with chronic renal failure, hypocalcemia contributes to the parathyroid hyperplasia and increased parathyroid hormone secretion characteristic of secondary hyperparathyroidism (sHPT). However, patients with uremia also display reduced sensitivity to extracellular calcium; this seems to be owing to an alteration of the receptor mechanism. This study examined calcium receptor expression in the parathyroid tissue of patients with sHPT, using immunohistochemical techniques and comparison with normal tissue and parathyroid glands of patients with primary hyperparathyroidism. In all the glands studied, immunostaining was more intense in chief cells than in oxyphilic, transitional, and clear cells. The parathyroid glands of patients with sHPT displayed significantly reduced expression of CaR with respect to morphologically normal ones; a very similar reduction is reported in adenomas. Furthermore, in glands displaying multinodular hyperplasia, expression was less marked in nodule-forming cells than in internodular areas. The decreased expression of calcium receptors in the parathyroid tissue of uremic patients was thought to be owing to the different cell populations present; these parathyroid glands contained predominantly transitional, oxyphilic, and clear cells, which normally express fewer receptors than chief cells, which are more abundant in normal glands.

Primary neuroendocrine carcinomas (NEC) of the sinonasal cavities are exceedingly uncommon and difficult to diagnose by conventional histologic examination. NEC are small cell neoplasms that show positive immunoreaction to neuroendocrine markers and lack of olfactory maturation. 1 The English-language literature consists of small series and isolated case reports, many of which are poorly documented, therefore retrospective analysis of published cases is difficult. In addition, a critical review of these reports indicates that some of the lesions described exhibited clinical or pathological features consistent with other diagnosis, and in particular with olfactory neuroblastoma (ON). 2 In this article, we describe a single case of NEC of the sinonasal cavities that clinically presented as a tumor of the nasopharynx.