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They are highly vascular, but run a slowly malignant course. They 

 are extremely rare. They have been seen the size of a pea occur- 

 ring on the Choroid Plexus and in the Lateral Ventricles (Cadeac, 

 Dexler), and the size of a nut occurring in the Parotid region 

 in two different animals (Lienaux). 



(a) Epithelial and Glandular Tumors Approximating to Fully 

 Formed Tissue. 



Adenomata. An adenoma is an innocent growth originating 

 from pre-existing glandular tissue and formed by proliferated 

 gland cells arranged in an orderly manner, and supported by a 

 fibrous stroma. But these cells differ from normal ones in that 

 they have no power of producing the normal secretion peculiar 

 to the gland tissue from which they grow. That is to say, if any 

 secretion at all is produced, it is a modified one, and the gland 

 has no means of discharging it externally by proper ducts. There 

 are adenomas of the liver which clearly show bile pigmentation, 

 and thyroid adenomas may lead sometimes to exophthalmic goiter 

 brought about by excessive production of excretion, which often 

 disappears upon removal of the tumors. Tumors of this class show 

 no tendency to infiltration of neighboring lymphatics, but under 

 certain conditions are capable of developing malignant characters. 

 (See Carcinomata). 



The adenomata are often of mixed type, such as fibro-adeno- 

 mata, myxo-adenomata. Common seats are the Mammary Glands 

 (Sutton), the Peri-anal Glands, the Prostate Gland, and the Se- 

 baceous and Sudoriparous Glands of the Trunk and Extremities 

 (Lienaux, Leisering, Siedamgrotzky). Other organs in which this 

 form of tumor has been observed are: Harder's Glands (Froeh- 

 ner), the Liver (Hobday), the Ovary (Sutton), the Vagina (Cam- 

 ardi), the Lungs (Stockman), the Thyroid (Woelfler), and the 

 Cerebrum (Penberthy). 



Lymphadenoma. This term is used to denote' a form of neo- 

 plasm affecting lymphatic tissues and having the structure of lymph- 

 adenoid tissue. It occurs as a purely innocent local affection, a 

 common seat of which is the spleen, and also as a more or less 

 malignant disease. The difference between the latter and splenic 

 leukemia and lympho-sarcoma has already been pointed out under 



