274 The Philippine Journal of Science 1923 



HISTOLOGY OF THE YAW 



The above observations on the histopathology of well-developed 

 early yaws agree in most particulars with those of previous in- 

 vestigators. I have been more impressed perhaps than the 

 majority by the degree of acute injury and reaction in the 

 papillae, especially in the earlier stages, and am of the opinion 

 that the first local inflammation occurs in this portion of the 

 skin, with secondary involvement of the epidermis. The 

 presence of acute exudate and focal accumulation of polymor- 

 phonuclear cells in the corium of the youngest papule studied, a 

 papule 2 millimeters in diameter from case 3, and the demon- 

 stration of treponemata in the perivascular tissues of papillae 

 in another fresh lesion (case 1), together with the recognition 

 of an apparent necessity for the secondary eruption of yaws to 

 begin with a localization of organisms from the circulating 

 blood about smaller blood vessels of the skin, have urged upon 

 me the acceptance of this conception of the beginning of the 

 lesions. 



The presence beneath the epidermis of treponemata of the 

 species Treponema pertenue has not to my knowledge been ob- 

 served before; and it is, indeed, a very curious fact that their 

 distribution in demonstrable numbers is practically always 

 limited to the epithelial layer. Here are certainly in later stages 

 the optimum conditions for their growth, notwithstanding the 

 fact that they may live in and be distributed by the circulating 

 blood. This strict limitation in distribution is a noteworthy 

 contrast to the disposition of the closely related Treponema 

 pallidum which seems to find a more-favorable environment in 

 connective-tissue spaces. 



The purulent exudate in the epidermis is undoubtedly a re- 

 action to the presence there of treponemata, and not a result of 

 secondary invasion by pyogenic cocci from the surface, as was 

 suggested by Unna who was not acquainted with the etiological 

 agent of the disease, and thought probable by Siebert who, 

 finding the treponemata only in association with the exudate, 

 was inclined to think this a prerequisite for their localization. 

 But the mass of leucocytic exudation and the greater number 

 of miliary abscesses are situated nearest the basal layers of 

 epithelium, and here treponemata are in greatest numbers and 

 other organisms are absent. Nearer the surface treponemata 

 diminish in numbers even in the miliary abscesses, and cellular 

 exudate is abundant, while on the surface bacteria are present. 



