This section is from the book "A Treatise On The Materia Medica And Therapeutics Of The Skin", by Henry G. Piffard. Also available from Amazon: A Treatise On The Materia Medica And Therapeutics Of The Skin.
Freckles, as is well known, are small pigmented macules which appear on the face, hands, and other exposed portions of skin during the warm weather, in those who are exposed to the direct rays of the sun. The active co-operation of this luminary in the production of Ephelis is well recognized, but why they should appear in abundance on the faces of some and not on others, is not known. It is generally supposed to denote a peculiarly delicate skin, but this explanation is not wholly warranted by the facts. Of three persons exposed at the same time and to the same solar influence, one may freckle, a second tan, and the third burn. Freckles are perhaps most frequently seen in blondes, but are by no means rare in brunettes, and we have even seen them in mulattoes. The color of the freckle itself varies in different persons, from a light yellow to a deep brown or blackish brown. As a rule, the degree of pigmentation of the freckle is in direct ratio with the normal degree of pigmentation in the individual bearing them; that is, blondes usually have light colored freckles, and brunettes darker ones.
Freckles usually appear at about the season when one naturally seeks the shady side of the street or road, continue in full efflorescence during the summer, and fade away as cooler weather sets in. Individual susceptibility, however, differs greatly in this respect, both as to the number of freckles and the date of the appearance; and in some they may be faintly perceived even in winter, to become more marked as the spring and summer advance.
* Mattelli: De l'Elephantiases des arabes et principalement de son traitement par la compression elastique. These de Paris, 1870.
It seems almost superfluous to speak of the diagnosis of so common an affection, especially as there is but one other that could by any chance be mistaken for it. I allude to Lentigo, a name often impproperly applied to the affection we are considering. Lentigo, like Ephe-lis, consists in small pigmented macules, but they do not appear to be due to solar influence, they are found on the covered as well as uncovered portions of the body, and do not undergo changes of hue during the different seasons. They are probably a localized excess of true pigment located in the deepest cells of the stratum Malpighii, while in Ephelis the discoloration is much more superficial.
As we do not know of any special internal cause that can be said to exert any influence on the development of freckles, we are, of course, deprived of any internal means of combating them, and are forced to rely on external measures alone. Of these any application that is capable of causing an exfoliation of the horny epidermis, will remove the freckle with it. Perhaps the most convenient application is a two to ten grain solution of the bichloride of mercury in cologne water, or other agreeable menstruum. When the freckles are few in number, a few applications of the lotion may be made to each one. If they are very numerous this will prove to be a tedious undertaking and is hardly to be recom-mended. Occasionally freckles are exceedingly numerous and almost confluent, so that there is really more freckle apparent than normal skin. In cases of this sort, if the patient insists on their removal, it may be effected at the cost of some pain by Hebra's method.
This consists in applying to the affected parts a compress, wet with a one per cent. solution of bichloride of mercury. The compress is kept moist and retained in place for four or five hours, until a blister forms. This is opened, the epidermis removed, and the part dusted with powder starch. The freckles will have been removed, but are likely to invade the new epidermis if again subjected to the exciting cause.