PATHOLOGICAL ANATOMY AND HISTOLOGY 799 



Before a diagnosis of sarcoma of the hypophysis is made a very thor- 

 ough examination should be made of sections especially stained to bring 

 out the intracellular granules. 



Tumors Arising from "Rests" of the Craniopharyngeal Duct. Erd- 

 heim(6) has described a very definite type of tumor in the region of the 

 hypophysis which develops from rests of the embryonic craniopharyngeal 

 duct. Along the anterior surface of the infundibulum there is a thin 

 layer, or tongue-like process of cells extending upward from the anterior 

 lobe. This process ends high up on the infundibulum in an "end-swell- 

 ing," which in about eighty per cent of adults 

 contains small groups of squamous epi- 

 thelium. There are similar small groups of 

 squamous cells on the front surface of the 

 anterior -lobe at the place of attachment of 

 the infundibular process. Such squamous 

 cells are not found elsewhere in the anterior 

 lobe. The tumors described and differenti- 

 ated by Erdheim originate from one or the 

 other of these two groups of squamous cells. 

 Their location, and their gross and micro- 

 scopic appearance are characteristic and 

 pathognomonic. 



These tumors vary somewhat, depending 

 upon whether they are benign or malignant, 

 and whether they originate from the upper 

 or the lower groups of squamous epithelial 



cells. All of them lie behind the optic chiasm, below the brain, above the 

 hypophysis, and within the circle of Willis. 



(1) If the tumor develops from the upper group of cells and is 

 benign, it is composed of one or more simple papillary cysts, usually filled 

 with clear fluid ; and is separated from the hypophysis by the dura mater 

 covering the sella turcica. Malignant tumors originating from this source 

 are solid; they invade and push upward the floor of the 3d ventricle of 

 the brain; invade the dura mater covering the sella and compress the 

 hypophysis. 



(2) A benign tumor originating from the lower group of squamous 

 epithelial cells appears as a cystic new growth lying below the dura mater 

 which it pushes upward. It flattens the hypophysis and is attached to its 

 surface. It may erode the bones at the base of the skull and even bulge 

 into the vault of the pharynx. If the tumor developing from this lower 

 group of cells is malignant, it first grows in the sella turcica as a solid 

 mass, invading and compressing the hypophysis ; it erodes the bone ; and 

 grows through the dura mater and infiltrates the under surface of^the brain. 



Historically, these tumors resemble adamantinomas, the similarities 



Fig. 8. Schematic drawing 

 to indicate the origin of cranio- 

 pharyngeal duct tumors. AL. 

 Anterior lobe. PL. Posterior 

 lobe. I. Infundibulum. E. Ex- 

 tension of cells of anterior lobe 

 upwards on front surface of the 

 infundibulum. UG. Upper 

 group of squamous epithelial 

 cells. LG. Lower group of 

 squamous epithelial cells. DM. 

 Dura mater. 



