CLINICAL CASES 45I 



the duct was retained on the right side, but had disappeared for the most part 

 on the left side, where it was replaced by an ingrowth of vascular glial tissue. 

 In the nerve-tissue of the splenium and quadrigeminal plate which surrounded 

 the growth there was a considerable increase in the number and size of the 

 blood-vessels. Many of these contained thrombi, in which there was a relatively 

 very high proportion of lymphocytes as compared with red blood-corpuscles. 

 The walls of the vessels were thickened, and there was a considerable nuclear 

 proliferation in surrounding glial tissue. 



The surface of the tumour was very irregular and in places lobulated. The 

 central parts were broken down, an irregular cavity being present in the lower 

 part of the section, with spaces running out from the main cavity into the central 

 axes of the lobules, where the destruction of tissue was less complete. The 



Ca. 



Fig. 303. — Case i. Small Cyst in Base of Tumour containing 

 Choroidal Villi. 

 Ca. : calcareous body. C.V. : choroidal villus, 



central axes of the lobules showed a canal which was in some places lined by 

 flattened epithelial cells, external to which was a layer of condensed glial tissue 

 continuous with that of the tumour. These spaces were for the most part 

 empty, but occasionally contained a small amount of cell debris or degenerated 

 blood-corpuscles. They probably represent remnants of the lumen of the 

 original pineal outgrowth which had become cystic. 



The tumour cells were loosely arranged in a lobular manner around these 

 cystic spaces, the lobules being separated by vascular ingrowths from the sur- 

 face. Two principal types of cell were present : the majority had spherical 

 nuclei, deeply stained with hematoxylin, and surrounded by a small amount of 

 feebly stained cytoplasm. Among these were larger cells with a feebly stained 

 round or oval nucleus. They appeared to belong to the supporting glial tissue, 

 which in some places formed a trabecular network similar to that seen in the 

 normal gland. No mitotic figures appeared to be present, though in some parts 

 the cells were of small size and closely packed together, suggesting an active 

 proliferation. In the upper part of the tumour there were extensive areas of 

 necrosed tissue showing an irregular fibrinous network containing degenerated 

 red blood-corpuscles and leucocytes, which were intersected by strands of 

 degenerated glial tissue. 



A small cyst lined by ependyma and containing choroidal villi was present 

 at the base of one of the lobules in the lower part of the tumour (Fig. 303). 



