22,8 Goodpasture: The Histology of Healing Yaws 277 



becomes more compact and transparent, and the surface, now 

 dry, assumes a bright pink color when the superficial scab is 

 removed. The fluid exudate and most of the leucocytes vanish, 

 leaving only a small cluster here and there, and numerous iso- 

 lated ones lying in interepithelial spaces. 



Most of the elevation of the early yaw is due to the fact that 

 the epidermis is turgid with fluid and cellular exudate, and the 

 initial shrinking and flattening result from loss of this exudate. 

 The fact that the early yaw remains turgid for long periods 

 before treatment presupposes a continuous injury to the vascular 

 bed within the elongated papillae with resulting dilatation of 

 veins, capillaries, and lymphatics, and a continuous outflow of 

 fluid and cellular elements. Following the destruction of trepo- 

 nemata the source of this irritation is removed and the vascular 

 channels rapidly repair. This is the first change in the inflam- 

 matory reaction. In sections from case 1, forty hours after 

 treatment, there were found some injured veins and capillaries 

 plugged with thick fibrinous thrombi, a condition not observed 

 in any untreated lesion. The dilatation of the vascular bed was 

 also less marked. 



With the restoration of blood vessels exudation is suppressed 

 and the excessive fluid present in the epidermis is rapidly removed 

 by surface evaporation and by absorption, resulting in the form- 

 ation of a dry crust. Surface epithelium, in the early stages 

 uncornified, and leucocytic exudate, including superficial miliary 

 abscesses, largely compose the structure of the superficial crust, 

 as is evident in sections. The remaining leucocytes not cast off 

 in the crust are removed in other ways. Thus we find in sections 

 that numbers of them are degenerated and necrotic. No doubt 

 a certain proportion die, disintegrate, and become absorbed with 

 fluid exudate. A larger proportion, however, are carried off 

 bodily by large mononuclear phagocytes. Shortly following 

 treatment the large phagocytes may constitute a conspicuous 

 element of the lesion. They are most abundant in the papillae, 

 where they have engulfed numbers of leucocytes; but they are 

 to be found wandering through intercellular spaces of the epi- 

 dermis picking up polymorphonuclear cells wherever they find 

 them. Even in the deeper exudate of the corium they are like- 

 wise prominent and active. They remove the leucocytes partly 

 by intracellular digestion in situ and by transporting them 

 through lymphatic channels to other places. Dilated lymphatics 

 in papillae are sometimes filled with them, each laden with disinte- 

 grating i 



