There is a general belief that actinic trauma is a factor in the causation or pathogenesis of lupus erythematosus. I have examined the literature in order to determine whether any correlation exists between the relative frequency of this disease and climatic conditions prevailing throughout the world. Adequate statistics based on large numbers are not always obtainable; it is often necessary to rely on the opinions of authorities based on personal observations over varying periods.
In the dermatologic clinics of the United States approximately 1 out of every 200 to 400 new patients has lupus erythematosus. The disease is, as MacLeod1 called it, one of the more common of the rarer dermatoses. Pollitzer2 gave the incidence as roughly 1 in 300. There is nothing in the voluminous literature on the disease to indicate that it is any more common in one part of the country than in any other