﻿yaws: a histologic study. 471 



new growth, but the most obvious changes occur in the epithelium. At 

 the edges of the ulcer there is a marked increase in the thickness of 

 epithelium and a striking increase in the number and size of the epithe- 

 lial downgrowths. Irregularities and distortions in the epithelial down- 

 growths are also seen beneath the surface of the ulcer, from which the 

 epithelial covering has been lost. (See PI. I, figs. 1 d: 2.) It is 

 evident that, while new growth of epithelium is occurring from the 

 columnar layer, degenerative changes are taking place in the older, more 

 centrally placed portions of the epithelial downgrowths. (See Pis. I, 

 IT, and III, figs. 1 c ; 3 a-; 4.) 



Tissues from these cases were treated by the method of Levaditi, 

 with negative results, but through the courtesy of Drs. Ashburn and 

 Craig I have had an opportunity to examine a successful silver stain of 

 a yaws papule prepared in Washington from tissue obtained in the 

 Philippines. In this section enormous numbers of spirochgetae are found 

 in the degenerating central parts of the epithelial downgrowths. The 

 spirochaetse are free in the necrotic material resulting from breaking down 

 of epithelial cells. None were found within cells, within nuclei, nor in 

 any part of the corium. 



SUMMARY OF FINDINGS. 



We may conclude from a study of these specimens, that we are dealing 

 with a primary degenerative change resembling colliquative necrosis, 

 affecting the epithelial structures and caused by spirochaetae, which are 

 very abundant in the necrotic material, at least at some stage of the 

 disease. The degeneration leads to ulcer formation. Following the 

 degeneration there is irregular, new formation of epithelium in the 

 form of downgrowths, which in turn often degenerate. Accompanying 

 these changes vascular dilatation, oedema and leucocytic infiltration occur 

 in the corium, with a minor degree of new formation of capillaries and 

 connective tissue. There is no endarteritis, nor are there any other 

 changes suggestive of syphilis. The majority of the infiltrating cells 

 are polymorphonuclears at an early stage of the lesion, while mononu- 

 clears, many of which are of the plasma cell type, are almost equally 

 abundant. Tn the tissue from the human being the plasma cells out- 

 number the polymorphonuclears. Polymorphonuclear eosinophiles are 

 abundant and have a peculiar distribution. 



The changes are essentially the same in lesions from monkeys and 

 human beings. 



The histological characteristics of the yaws nodules have been studied 

 by Charlouis, TJnna, G-logner, Plehn and others. 



Charlouis (Vierteljahresschrift (Archiv) f. Dermatologie und Syphilis (1881), 

 431, quoted by TJnna and others) describes particularly the epithelial over- 

 growth and the leucocytic infiltration, the hair follicles escaping, while the 

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