DERMATITIS PRATENSIS 



2033 



Govered by masses of scales, both on its free surface and on the sur- 

 face looking towards another process. 



This epidermis shows the defect of cornification called ' parakera- 

 tosis ' by Auspitz, while with regard to the rete there is a certain 

 degree of acanthosis. 



The corium is full of dilated vessels, and is also slightly oedematous 

 and fairly cellular. 



The cells consist of forms with a large, well-stained nucleus and 

 a fringe of cytoplasm, which are supposed to be derived from con- 

 nective tissue ceHs. Plasma cells and mast cells may also be seen, 

 aslmay an occasional polymorphonuclear leucocyte. 



Fig. 799. — Dermatitis Pratensis 



Turning now to the non-papillomatous regions, there is a well- 

 defined epidermis with parakeratosis and acanthosis, while the 

 cellular infiltration of the corium is denser. It is somewhat 

 oedematous. 



Raw areas show parakeratoses, which are distinguished by the 

 extraordinary development of the acanthosis. 



In the region where the epidermis is missing all trace of a normal 

 corium is lost superficially, and its place is taken by a fibrocellular 

 exudate. 



Embedded in this exudate can be seen the remains of the acan- 

 thotic prolongations of the epidermal cells. 



In this fibrocellular mass lie numerous bloodvessels filled with 

 corpuscles, while patches of serous exudation can also be observed. 



The cells of the mass are largely composed of the same cells as in 

 the corium of other pieces, but the amount of polymorphonuclear 



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