(Pityriasis rubra pilaris; Lichen ruber acuminatis)
Definition. A chronic, mildly inflammatory disease of the skin, characterized by the appearance of small, reddish, conical papules, chiefly situated at the mouth of the hair-follicles. These papules, by multiplication and aggregation, may form large infiltrated scaly patches, causing an apparent deepening of the natural lines of the skin.
Symptoms. The disease may be readily described in a number of stages. The first is known as lichen ruber papulosus, in which the papules are isolated and limited to the hair-follicles, but not invariably so, because they may be seen at an early stage upon the palms of the hands, where hair-follicles do not exist. At first, pin-head to millet seed in size, smooth and pale or yellowish red in color, they soon become tipped with a horny, adherent scale, and in some localities, as the dorsal aspects of the fingers, horny processes may protrude from the apex of the papules. In other localities, they present an appearance like goose-flesh, and as they multiply, feel like a nutmeg greater. They show no tendency at any time to become vesicular or pustular, and when fully developed do not change in size. It is the development of new papules between the earlier lelisons which changes the objective appearance, causing the formation of infiltrated patches and accentuating the furrows of the skin. This disease may become generalized over the surface by gradually development, but it usually shows a preference for certain localities, as the upper and central part of the back, the nape of the neck, sternoclavicular regions, folds of the axilla, elbows, knees, loins, genital regions and nates, the dorsum of fingers, the palms, the dorsum and soles of the feet. Scaliness is least apparent where the friction of the clothing is greatest. Hence the eruption may be largely modified by its situation. On the palms and soles, where the skin is thick, the papules may not show clearly, though they always precede the formation of thickened, scaly patches, which later on become fissures; while on the back of the fingers where there is no pressure, they may remain unchanged for a long time. If the horny sheath around the hair is torn away, and the dilated follicle exposed, it will soon fill again with a blackish collection of horny epithelia and sebum, which will plug the follicles and cause conical elevation. Though in many instances the papular character of this lesion is lost, it is only after the papules have fully multiplied and formed patches that the areas become uniformly scaly, although they may be surrounded by some isolated papules.
Lichen ruber squamosus, the squamous form, shows a large latitude in the degree of scaling. When abundant, there is a white, fleece-like layer of branny scales, unlike that of any other disease. More often, while the scales are of a snowy appearance, they do not entirely hide the lines of the skin, or only completely cover a patch for short time. The squamous patches vary in shape, largely according to the region involved. Over the spinal regions, around the waist, or on the extremities, they may appear oblong or in wide band-like forms. In the various flexures, they may be oval or spindle-shaped; while on the palms they may assume annual outlines, and on the trunk and extremities smaller patches may become discoid or corn-like in shape. When the scales become rubbed off, or are gradually shed, the affected skin presents a striated appearance on the lines of the normal folds. This may not be marked upon the parts not subject to much motion, but over the joints, buttock, etc., liable to frequent tension the wrinkled aspects may be so marked as to totally change the objective feature of the disease.
In the form known as lichen ruber rugosus, the thickened skin forms furrows running in one direction. Occasionally these may be intercepted by less marked lines running at right angles. In this stage the scaliness is scant; hence the condition of the skin is clearly apparent. Like the abundant scaliness of the squamous form, the parallel seaming of the skin is typical of this stage of the disease. In these advanced stage, the hands may undergo atrophic changes, resulting in the impairment of motion and the overprominence of joints. The nails may take on hypertrophic changes, becoming thickened, rough, and darker in color. A rare form of the disease has been described as lichen ruber moniliformis, in which the papules occur in beaded lines.
While the three common forms of lichen ruber may be successive stages of the same disease, they may be found coexistent, they may have periods of alternation, or they may be recurrent. The disease may be arrested in its papular stage, but more often reaches the squamous type, to persist with a shifting of location for years, often never developing pronounced furrowing. Itching is not pronounced in the papular form but may be severe in the later stages.
Etiology and Pathology. Heredity, age, sex or color have no etiological bearing, although the disease attacks males oftener than females, and is more common in children and young adults. That it is probably due to some obscure condition or diathesis is probable from the fact that when the disease exists, slight local injury, such as the scratch of a pin, may cause the appearance of additional lesions at the site of injury. But nothing positive is known as regards the etiology. The essential pathological lesion is a follicular hyperkeratosis, and cannot be said to be typical of lichen ruber. Some believe with Kaposi that the inflammation of the corium is primary, and that the epithelial changes are secondary; while others agree with Robinson that the hyperkeratosis is primary, and that the vascular dilatation, enlarged papillae and other changes in the skin are secondary.
Diagnosis. Widely distributed papular eczema might be mistaken for lichen ruber, but the former does not present uniform papules with white patches. Psoriasis would show punctate papules extending peripherally, whereas may be easily confused with the generalized form of psoriasis, but the former usually has less abundant scales, and greater infiltration, and the palms and soles are relatively more often and more intensely affected than in psoriasis. Lichen planus is characterized by an eruption of flat, angular, shining and umbilicated papules, of a dull red color and isolated at first, but later coalescing, assuming a purplish hue and becoming covered with thin scales.
Prognosis and Treatment. The former is generally unfavourable for a permanent cure, although many cases do not run through the three stages of the disease, and may disappear spontaneously. Recurrence are common, but fortunately the large percentage of fatal cases noted by Hebra many years ago, has disappeared.
The most important therapeutic item is, to improve physiological living; that is, to regulate the quality and quantity of food and drink, exercise, bathing, and the promotion of the secretions of the body. Locally, the skin needs mechanical protection and first measure may be obtained by the application of bland fats or oils, used as often as may containing salt, borax, or bran, or a Turkish bath may suffice. But in the case of bathing, oily applications should immediately follow on drying the skin. Unna;s salicylic acid plaster may be used to remove patches Pyrogallic acid, tar and chrsarobin may be employed depending upon the necessity of the case. The high-frequency currents and X-rays have been used, both to stimulate surface conditions and to decrease the itching. The ordinary carbolic acid and calamin ointments and lotions will assist to relieve the itching. While Arsenic and its salts, particularly Nat. ars., is more often indicated than any other drug, it is well to study to totality of symptoms. Mercurius cor. has given good results in a number of cases.