Thyroid gland description

Since its description in 1975, painless (sUent, lymphocytic, postpartum) thyroiditis has been recognized as a common cause of thyrotoxicosis and may represent up to 15% of cases of thyrotoxicosis in North America. The etiology is not fully understood and may be heterogeneous. The triphasic course of this illness mimics that of painful thyroiditis. Most patients present with mild thyrotoxic symptoms. Lid retraction and lid lag are present but exophthalmos is absent. The thyroid gland may be diffusely enlarged but thyroid tenderness is absent. 

Commercial PCB Mixtures. Various effects on the thyroid gland and thyroid hormone system have been observed in rats exposed to Aroclor 1254 by the oral route. Descriptions of the histological changes in the rat are reasonably consistent across studies. Typical findings, depending on the dose, include hyperplasia, hypertrophy, and increased vacuolization of follicular cells, depletion of follicular colloid and reduced follicular size, and thyroid enlargement (Collins and Capen 1980a Collins et al. 1977). 

The thyroid gland may be damaged in many ways. A comprehensive description of the anatomical pathology of the thyroid will not be attempted, but since the pathogenesis of hyper- and hypothyroidism cannot be properly understood without an adequate morphological description of the lesion, the major forms of thyroid injuries are outlined (see Table 8-5). The reader is referred to specialized books for further information on the anatomical pathology of the thyroid. 

Three famous physicians have contributed to our early knowledge of hyperthyroidism. Parry, an Englishman, described the disease but left it to his son to publish, in 1825, the first description of hyperthyroidism. In 1835, Graves, an Irish physician, attracted attention to the relationship between some symptoms now known to be associated with hyperthyroidism and the thyroid gland. Von Basedow in 1840 meticulously described the complete clinical symptomatology of hyperthyroidism [36]. 

The term H N cancer describes those cancers arising from the mucosal lining of the upper aerodigestive tract and major specific structures within this anatomical area, especially the four major salivary glands and the thyroid gland. The area covered by this descriptive term is shown in Figure 10.1. 

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