PATHOLOGICAL ANATOMY AND HISTOLOGY 573 



hyaline degeneration of the stroma in support of this. In similar cases, 

 the arterial walls show bandlike hyaline structures or deposits which 

 have been referred to in the literature as amyloid. It is unusual to obtain 

 chemical reactions for amyloid. Cysts which have developed from the 

 colloid containing acini may continue to enlarge and subsequently con- 

 tain a thin serous fluid. These are subject to hemorrhage as are those 

 of the thyroid. The epithelial cells, responding in hyperplasia or tumor 

 formation, as well as those lining the cysts, are the basophilic, normally 

 forming the chief elements of the glandules. These cells may be arranged 

 in nests, rows and columns, or they may appear in aggregations in which 

 many of the centrally lying cells do not appear to rest directly upon the 

 stroma. Vacuolation and hydropic degeneration of the parenchymatous 

 cells is not uncommon. Less commonly, cysts may take origin from lym- 

 phatics, remnants of congenital parabranchial tubules and implantation 

 masses of thyroid or thymus. 



Metastatic Tumors. The metastasis of secondary malignant tumor 

 into the parathyroid glands is still less frequent than the development of 

 primary tumors. Only a few cases have been recorded. The first of these 

 was by Koenigstein, who reported a metastatic adenocarcinoma which in- 

 volved a considerable region of the neck, including all four parathyroids. 

 Three of these glandules were so disturbed that nothing remained of their 

 normal structure. Koenigstein remarks upon this extensive infiltration and 

 the absence of any manifestations of tetany. Pepere (a) observed the infil- 

 tration into the parathyroid tissues of a malignant growth arising in the 

 thyroid. In a second case, the same author reports upon the occurrence 

 of metastases from a cancer of the breast. Thompson (c) also reports two 

 cases, the first occurring in a woman of thirty-two, who died of extensive 

 carcinomatosis following cancer of the breast; in this instance all four 

 parathyroids were occupied by metastatic growths. The second case was a 

 male aged sixty-seven, who died of mediastinal lymphosarcoma, in whom 

 three of the four parathyroids were occupied by secondary tumors. The 

 author also noted the absence of any signs of tetany in both of these cases. 

 These findings, he states, bear out the experimental work in which it has 

 been shown that the parathyroids may be gradually destroyed without 

 symptoms of tetany. 



The Parathyroids and Bone. Relation to Calcium Metabolism of 

 Bones and Teeth. A considerable relationship has been suggested be- 

 tween the functional activity of the parathyroid and the quantitative dis- 

 tribution of calcium salts in the body. It has further been observed by 

 Kassowitz that tetany in children is not uncommonly associated with 

 rickets, in which improper metabolism of calcium salts may otherwise 

 be demonstrated. Erdheim observed that the extirpation of the para- 

 thyroids of rats leads to the development of imperfect teeth (incisors), 

 poor in calcium. In later experiments, it was still further shown that 



