In spite of the enormous amount of literature lately evolved on this subject, little has been presented that throws light on the true character of the growth. This statement was recently made by W. Risel, and I think we must all agree with him.
Progress has been made in the study of the histology of these growths, and we have arrived at a more definite understanding of certain points in the histogenesis which were formerly much discussed.
The term deciduoma malignum, introduced by Sänger, has been abandoned, and it is generally conceded that this growth, composed as it is of Langhans'1 cells and syncytium, arises from the fetal ectoderm. But we seem to have been led into still greater confusion by the recent reports of cases of primary chorio-epitheliomatous growths arising outside of the placental site, and these not confined to the female, but found as well in the teratomata of the testicle.