(Lichen ruber planus)
Definition. An inflammatory disease of the skin characterized by an eruption of flat, angular, shining, umbilicated papules. Of a dull red color, and isolated at first, they may coalesce into linear or irregular patches, assuming a purplish hue and sometimes covered with thin scales.
Symptoms. This disease is not uncommon in this country, although modern in identity, having been first described by Erasmus Wilson in 1869. It always begins with the formation of discrete papules which become slightly elevated, smooth, angular, with a pit-like, depressed center. They are varied in color from a crimson red to a lilac hue, and in size from a pin-head to a bean. Although these characteristics may vary widely in different cases, both size and color are apt to angular they are in shape, some of the smaller ones being rounded. They show a tendency to symmetry and a preference for certain locations, such as the flexor aspects of the wrist and forearm, dorsal surface of the hands, inner side of the knee and the waist above the hips, but they may occur upon any part of the external surface, or upon the mucous membrane of the mouth. When patches are formed, it is not by enlargement of the papules, but by their multiplication, as in lichen ruber. The surface appearance is a grayish translucence, and will often show, upon careful view, typical gray points or striae. The patches are small, often in lines or oblong shapes, parallel with the length of the limb, although sometimes they run transversely and less frequently circular forms may be seen. Although this disease is never universal to the extent that lichen ruber may become, patches may very rarely become extensive and involve a large portion of the surface.
The disease may assume atypical forms when the eruption appears in unusual locations. Thus a considerable thickening of the diseased skin is called lichen planus hypetrophicus, papillary outgrowths form lichen planus verrucosus, and dense horny scales comprise lichen palnus corneous. Vesicles, bullae and pustules never develop directly from the papules of lichen planus, but they may be found associated with them, and the patches may even become the seat of ulceration. As a rule, no distinct scaling is present, but the itching in most cases is a prominent and annoying feature. While usually slow in both evolution and involution, the eruption may appear rapidly only to run a chronic course or it may be acute or chronic throughout. The duration is variable lasting from weeks to years. Relapses are common, but distinct recurrences are rare.
Etiology and Pathology. This disease is clearly of neurotic origin, the commonest cause being nervous exhaustion from anxiety, overwork, strain and worry, deficient or improper food and digestive disturbances. It is a disease of middle adult life, rare in children, although it has been observed in the very young and the very old. Microscopic examination shows that the hair-follicles and sebaceous glands are not affected. The characteristic feature is the marked definition of the affected papillae and subpapillary layer from the normal tissue beneath. The papules are found chiefly at the mouth of the sweat-glands, although the glands themselves are seldom involved, and appear to be due to a circumscribed cell-infiltration of a lymphoid nature in the papillary layer of the corium.
Diagnosis. The flat, angular, smooth, shining, umbilicated, purplish papules are never seen in any other disease, and there should be no difficulty in the diagnosis of a typical case. But even in atypical cases, enough of these characteristic symptoms are present to differentiate similar appearing cases of psoriasis, papular eczema or lichen ruber. For further differentiation from lichen ruber, see that disease.
Prognosis and Treatment. Although the itching causes much discomfort and the eruption may persist through a chronic course, recovery usually follows, sometimes spontaneously, even unexpectedly, and the general health suffers little.
From its probable neuropathic and diathetic nature, it is apparent that all that pertains to a more normal living should be investigated, as diet, exercise, clothing and general habits. Often change of season, of climate, of occupation, with the necessary non-alcoholic toncis, or the general application of the high- frequency currents, will benefit. Bland oils or fats, and alkaline baths may be made use of, both for protection and as a preliminary to further antipruritic treatment. For the itching, liquor carbonis detergens, 1 to 50 per cent. (gradually increasing) in solution or ointment; carbolic acid, 2 to 5 per cent. with boric acid, 10 per cent. used in the same manner; or calamin, two drams, glycerin and rose water, each a one-half ounce to three ounces of milk of magnesia, may be selected. Local pathogenetic remedies may be needed for chronic, infiltrated patches, such as 10 to 20 per cent. salicylic acid ointment, a 50 per cent. solution of hydrogen peroxid, mild X-raying applied bi- weekly, or high-frequency sparking. Phototherapy has also been recommended for localized areas. For internal medication, see Anacard., Arsen., A. hyd., A. iod., Berberis, Kali carb., Ledum., Mangan., Mercurius vivus. M. cor., Nat. mur., Nux vomica.