PATHOLOGICAL ANATOMY AND HISTOLOGY 797 



the anterior lobe, and very rarely, if ever, in the central portion. The 

 hypophysis as a whole may or may not be enlarged. The largest hypophy- 

 sis is Kraus' series of cases measured 3 by 3 by 4 cm. On account 

 of the nature of the lesion the surface of the hypophysis is likely to be 

 irregular in those instances in which the adenoma or adenomas acquire 

 considerable size. 



Microscopically, an adenoma is composed of epithelial cells arranged 

 in cords, with occasional alveoli, and having the characteristics of one or 

 another of the cell types 

 commonly found in the 

 anterior lobe. In Kraus' 

 (c) series there were 

 chromophobe, transi- 

 tional, eosinophil, baso- 

 phil, and pregnancy cell 

 adenomas. The gran- 

 ules in an adenoma are 

 usually less abundant 

 and sometimes stain less 

 deeply than in the cor- 

 responding cells of the 

 normal portion of the 

 anterior lobe. They 

 also contain less fat and 

 lipoids than those of the 

 adjacent glandular por- 

 tion. Mitotic figures 

 are only very rarely 

 observed. 



The adenomatous 

 mass is distinctly differ- 

 entiated from the surrounding anterior lobe, although frequently there is 

 no definite connective tissue capsule. 



It is uncertain whether these circumscribed masses are truly neoplastic 

 in nature, or are, rather, a definitely localized hyperplasia similar to the 

 nodules found in struma nodosa of the thyroid (v. Gierke). These 

 adenomas are not uncommon in persons over 40 years of age. In Kraus' 

 series of 25 cases, only 3 were under 30 years of age, while only 6 were 

 less than 40 years old. 



Carcinoma. Neoplasms which originate in the anterior lobe, break 

 through the capsule and infiltrate the adjacent tissues, and even erode 

 and invade the sphenoid bone, are occasionally met with. These tumors 

 possess all of the criteria of malignancy except the production of metastases 

 at a distance from the primary tumor. Most of the cases reported in the 



Fig. 7. A chief cell adenoma of the anterior part of 

 the anterior lobe of the hypophysis. Magnified 24 times. 

 Its peripheral position is indicated by the capsule of 

 the gland seen in the lower left hand segment. 



