The etiology of lupus erythematosus remains to the present day an unsolved dermatologic problem, in spite of the somewhat commonplace character of the affection, and the large number of careful and painstaking researches in that direction. Its frequency, notwithstanding its world-wide distribution, is variously estimated. From the records of the American Dermatologic Association it occurs once in three hundred dermatologic cases in the United States, with marked fluctuations with respect to locality. Voirol1 reports only one case in every 833 cases of a dermatologic nature in Berlin; Crocker reports one in every 55 cases in private practice in London, and Jadassohn2 one in every 66 cases (in private practice in Berne), and one in every 78 cases in dispensary and hospital practice.
This seeming disparity is probably more dependent on factors pertaining to personal observation, particularly the ease with which the acute disseminated forms, and mild chronic circumscribed