22, s Goodpasture: The Histology of Healing Yaws 273 



The cellular exudate in the deeper portions of the corium ap- 

 pears the same as in the previous section, unless there is a 

 relative increase in the number of polymorphonuclears and 

 lymphocytes, and more hyalinization of plasma cells. 



Levaditi preparation.— Sections stained by Levaditi's silver 

 method show no treponemata. The pigment strands of the 

 stratum germinativum stain conspicuously. 



Yaw 3. — On September 9, the yaws were changed still more in 

 gross appearance ; since the 5th they assumed a dark slaty color, 

 having lost completely their red tint. They were drier and 

 beginning to form a scaly crust (hyperkeratosis) , loosened about 

 the margins. 



Under local anaesthesia Doctor Franco removed a yaw meas- 

 uring 0.7 centimeter in diameter. Cut sections show an ir- 

 regularly thickened and firm epidermis, but the general consis- 

 tency, especially of the corium, is softer than that of previous 

 lesions. The corium has a slaty color. 



Sections, microscopically, show a continued progress toward 

 normal skin. Except for a slight excess of interstitial fluid in 

 some of the papillae there is a complete absence of evidence of 

 acute inflammation. There are no polymorphonuclears, and 

 both lymphatics and blood vessels have resumed their usual size. 

 The epidermis is becoming rapidly readjusted. It is much 

 thinner than in the previous sections and there is marked hy- 

 perkeratosis. Even in the deep epithelial pegs there is advanced 

 keratosis, great central whorls of keratinized cells giving the ap- 

 pearance of small dermoid cysts. Individual epithelial cells are 

 nearing the normal size and degree of compactness. There is 

 a greater abundance of pigment in the form of large branching 

 strands and of intra-epithelial granules situated in the stratum 

 germinativum. There is also an abundance of pigment-bearing 

 cells in the corium, which evidently gave the slaty tone noted in 

 gross. The connective tissue of the corium is compact, but there 

 is little change in the mononuclear exudate present in this layer. 

 It remains abundant and composed of plasma cells and lym- 

 phocytes. Plasma cells are relatively less numerous than in 

 previous sections, and hyalinized forms seem to be increased in 

 number. There are less eosinophiles than previously noted and 

 practically no polymorphonuclear cells. 



Levaditi preparation. — Levaditi's method discloses no trepo- 

 nemata in the lesion. 



