296 REPORT OF THE HARVARD AFRICAN EXPEDITION 
downgrowths of the epithelium into the corium have occurred (No. 222). 
The papillae, however, are generally not well marked and do not extend to a 
great depth into the epidermis, and while a few are increased in length none are 
seen to reach at the surface to near the corneal layer. In some areas the papillae 
have disappeared. The prickle cells in some places show considerable and ap- 
parently a normal amount of pigment, but in other areas the pigment is almost 
entirely absent from them. The epidermis is not infiltrated with leucocytes and 
the pathological changes are much more marked in the corium than in the epi- 
dermis. In the corium there are observed in all the pieces of tissue a few epithelial 
pearls resembling those seen in epidermoid carcinoma. In the corium also there 
is especially a large amount of newly-formed connective tissue showing in many 
areas very extensive cellular infiltration. The papillae share to some extent in 
this infiltration, but it occurs more especially below them and in the deeper 
layers of the corium. 
The cellular infiltration consists of proliferated endothelial cells, fibroblasts, 
plasma cells, and small round cells. In many instances it is diffuse, while in 
others it exists in broad more or less longitudinal bands, or in clumps in the 
corium. In still other places it is distinctly nodular in character and tubercle-like 
in structure (Nos. 220, 221). 
Giant cells are also numerous and are particularly present in the nodular 
areas where there are also numerous epithelioid cells and much proliferation of 
the fibroblasts and numerous round cells. In some instances the large areas of 
cellular infiltration are surrounded by rather dense fibrous tissue in which nuclei 
are not abundant. Many of the blood vessels show endarteritis, proliferation of 
the endothelial cells and thickening of the walls, though there is not marked 
evidence of periarteritis and extension of the endothelial cells into the surround- 
ing tissue. The condition might suggest syphilis, but the numerous giant cells 
in the corium (and not in the region of striped muscle) are not in accord with 
such an idea. 
The condition also suggests tuberculosis, but the case, from a clinical stand- 
point, did not suggest tuberculosis and no tubercle bacilli could be found in any 
of the many sections studied. Although leprosy had been suggested by some of 
the clinical features, leprosy is not particularly suggested by the pathological his- 
tology. The “lepra cells” are not present, and in lesions of this nature if the 
condition were leprosy, one might expect that lepra bacilli would probably be 
plentiful. 
Giant cells are not a feature of primary or secondary yaws, though they are, 
of course, sometimes found in the tissues from yaws cases. 
The lesions in this case give evidence of a chronic inflammatory process 
with formation of much granulation tissue in which, however, the more acute 
process of the disease has been arrested. Polymorphonuclear leucocytes play a 
very small part in the infiltration. The more acute degenerations of the newly- 
formed tissue commonly observed in yaws and syphilis are no longer occurring 
in this case. However, the numerous scars on the skin give evidence that 
apparently previously an ulcerative stage of the disease existed. 
